DDDR/2 - Physical Video Device Drivers

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Display Device Driver Reference
  1. 16-Bit VGA Display Driver
  2. 8514/A Display Driver
  3. 32-Bit VGA Display Driver
  4. 32-Bit Super VGA Display Driver
  5. SVGA Base Video Subsystem
  6. Physical Video Device Drivers
  7. Virtual Video Device Drivers
  8. Seamless Windows Support
  9. PM Palette Management Support
  10. Distributed Console Access Facility (DCAF)
  11. DBCS Video Driver Support
  12. Installing and Configuring Display Device Drivers
  13. Graphics Test Suites
  14. Display Test Tool
  15. VIDEOCFG.DLL Exported Functions
  16. VIDEOPMI.DLL Exported Functions
  17. VIDEO Protect-Mode Interface
  18. Data Types
  19. S3 Display Driver
  20. Notices
  21. Glossary

Reprint Courtesy of International Business Machines Corporation, © International Business Machines Corporation

Contents

Physical Video Device Drivers

Video devices are accessed by using Base Video Handlers (BVHs). These BVHs consist of one or more Dynamic Link Libraries (DLLs). In the representative case of the VGA, BVHVGA.DLL manages the device for full-screen sessions, while DISPLAY.DLL (renamed from IBMVGA.DLL) manages the device for the Presentation Manager interface. Although these device handlers are initialized by different sections of the system at this time, they are architecturally compatible and can easily be combined at a later date.

Video Device Handler Identification

The list of the active video device handlers and their components resides in the CONFIG.SYS file as environment variables. To conserve environment space, these variables are removed from the environment during Shell Initialization. The VIDEO_DEVICES environment variable lists the names of the environment variables that describe each of the video device handlers. Commas are used to separate the names in this list. The following is an example of how to specify the environment variables ARTICHOKE and WATERMELON as those defining the active video device handlers, with ARTICHOKE used as configuration number one, and WATERMELON used as configuration number two.

SET VIDEO_DEVICES=ARTICHOKE,WATERMELON

The value of each environment variable that describes a video device handler is composed of three keywords and the values associated with them. These keywords are separated by blanks and can be specified in any order and in any combination of upper and lower case characters. The DEVICE() keyword defines the list of names of the dynamic link libraries and physical device drivers which are combined to create the video device handler. The names are separated by commas, and their order determines the order in which the components will be initialized. These names represent only those parts of the BVH that need to be called to initialize the Call Vector Table. That is, physical device drivers should not be included in the list if they are only called by the dynamic link libraries and do not directly modify the Call Vector Table.

The default initialization entry point name for the dynamic link libraries is DEVENABLE. An alternate entry point name can be specified by following any DLL name with +AltName, where AltName is the entry point name.

The default initialization IOCtl for physical device drivers is Function 73h. An alternate function number and category can be specified by following the device name by +Func+Cat, where "Func" is the function number and "Cat" is the category. Both numbers must be specified in hexadecimal form. For details, see Function 73h under "Physical Device Driver Initialization" later in this chapter.

The following is an example of a device handler that is composed of two physical device drivers, DEV1 and DEV2, and three dynamic link libraries, DYN1 through DYN3. The second physical device driver uses an alternate initialization IOCtl and the third dynamic link library uses an alternate initialization entry point. POINTER$ is the default physical pointer device driver.

SET ARTICHOKE=DEVICE(DEV1,DYN1,DEV2+74+05,DYN2,DYN3+OTHERENT)

DosOpen is called for each name in the list to check if it is a device driver with an associated "DEVICE=" statement in the CONFIG.SYS file. If the call fails, DosLoadModule is called to check if it is a dynamic link library. If both of these calls fail for any name in the list, the entire device is ignored.

If the optional PTRDEVP() keyword is specified, it defines the names of the physical pointer device drivers. If it is not specified, it defaults to PTRDEVP(POINTER$). The following is an example of a device with only one dynamic link library component and a unique physical pointer device driver for protect mode.

SET WATERMELON=DEVICE(SEEDLESS) PTRDEVP(PPOINT)

Note: This design is not limited strictly to physical video devices. By writing a device handler, video data could be written to any device, such as a printer or a plotter. In addition, by using alternate initialization entry points, multiple devices can be handled by the same physical device handler.

All of the video device handlers shipped with OS/2 2.1 are dynamic link libraries. They can be defined by the following environment variables, which use the default keywords of PTRDEVP(POINTER$) and PTRDEVR(POINTER$).

SET VIO_IBMMPA=DEVICE(BVHMPA)
SET VIO_IBMCGA=DEVICE(BVHCGA)
SET VIO_IBMEGA=DEVICE(BVHEGA)
SET VIO_IBMVGA=DEVICE(BVHVGA)
SET VIO_IBM8514A=DEVICE(BVHVGA,BVH8514A)
SET VIO_IBM8514A=DEVICE(BVH8514A)
SET VIO_IBMXGA=DEVICE(BVHXGA)

The following statements define a system with an 8514 display attached to an 8514/A as the only active video device:

SET VIDEO_DEVICES=VIO_IBM8514A
SET VIO_IBM8514A=DEVICE(BVHVGA,BVH8514A)

However, the statement below defines a system with an 8514 display attached to an 8514/A, and another PS/2* display attached to the VGA connector, as independent video devices.

SET VIDEO_DEVICES=VIO_IBMVGA,VIO_IBM8514A
SET VIO_IBMVGA=DEVICE(BVHVGA)
SET VIO_IBM8514A=DEVICE(BVH8514A)

Two other device handlers are provided with OS/2. The names of these device drivers are fixed. The Base Video Subsystem loads them automatically as they are needed.

BVHINIT.DLL is the generic device handler used by system installation and system initialization. It provides the minimum function necessary to support installation of the system and reporting of system errors during startup. It is loaded only if no other BVHs are successfully loaded.

BVHWNDW.DLL is the device handler that can support VIO window sessions and that provides the interface to the Presentation Manager interface by treating the PM interface as a virtual video device driver. BVHWNDW.DLL is loaded only for VIO window sessions.

Video Device Chaining

Video device handlers (BVHs) can be chained together when multiple BVHs share the responsibility of supporting a specific video adapter. This is accomplished by allowing previously loaded BVHs to attempt the handling of BVH functions. BVH8514A and BVHXGA are chained BVHs shipped with the product that provides this support.

A VGA and 8514A Scenario

During system initialization, BVHVGA is first called to initialize the Call Vector Table, that is, the table used by BVS to give control to the BVH routines. BVHVGA functions as though no other BVH will be handling the device. Next, BVH8514A is called to initialize the same Call Vector Table. However, BVH8514A saves a copy of the Call Vector Table before changing it.

When calls are made to this chained BVH, BVH8514A receives the call and passes it to the BVHVGA routine through the saved Call Vector Table. If an error occurs or if the results of the routine need to be modified, BVH8514A handles the call. Thus, BVH8514A uses the BVHVGA routines to perform all common functions. Device chaining can be viewed as a mechanism to allow one BVH to filter function calls to another BVH.

Primary Display Identification

The primary display is the default display chosen by VIO for full-screen sessions. It is also the display on which VIO and hard error pop-ups are shown. Notice that the primary display used by VIO is not necessarily the display on which the Presentation Manager environment runs. The Presentation Manager interface normally runs on the highest resolution display. In a dual-display configuration, the highest resolution display is not necessarily a display that can be used in text mode.

The primary display is the pop-up display. A physical video device driver must determine if it represents the pop-up display. If so, the video device driver must specify that it represents the pop-up display configuration in Query Config Info.

WrtToScrn/Panic Write Support

Before the video subsystem is loaded, and when the system is about to abnormally terminate, messages are sent to the screen by the WrtToScrn function, also known as Panic Write. This function switches to real mode and executes the INT 10h function to set the video mode to a text mode ( BIOS mode 3). It then uses BIOS INT 10h, "Write TTY", to display the message.

However, adapters such as the 8514/A have native modes that cannot be changed by INT 10h. In such cases, the BVH must include a Level 0 device driver that hooks INT 10h to provide extended set mode support. This hook must force the adapter out of its native mode, and then pass control to the previous INT 10h support. If these conditions are not satisfied, the adapter should not drive the power up display.

System Installation

The generic device handler, BVHINIT.DLL, is used primarily by system installation. It is also used for those situations when video devices have not been identified in the CONFIG.SYS file. It provides only the functions required for system installation and is otherwise device-independent.

Through VioGetConfig BVHINIT.DLL reports the highest function video adapter and display it can identify. It can identify only the MPA, CGA, EGA, VGA, 8514A, and XGA, along with their respective displays. Although it does not support mode and font setting, it attempts to load the 850 code page for the current EGA or VGA mode during system initialization.

If video devices have not been identified in the CONFIG.SYS file, the generic device handler attempts to load each of the following devices, until one is successfully loaded:

GENERIC=DEVICE(BVHVGA,BVH8514A)
GENERIC=DEVICE(BVHVGA)
GENERIC=DEVICE(BVHEGA)
GENERIC=DEVICE(BVHCGA)
GENERIC=DEVICE(BVHINIT)

Loadable Device Drivers

Loadable device drivers present a unique problem when used to support video devices because some video support can be required before the DEVICE= statements have been processed by system initialization. To handle this problem, two different initialization calls are made.

The Enable subfunction determines which type of initialization is to be done. If the subfunction is 1 (Fill Logical Device Block), the DevEnable function is requested to add all of the functions supported by the device handler to the Call Vector Table. If the subfunction is 3 (Fill Initialization Device Block), the InitEnable function is requested to add only those functions, that can be supported without the use of a loadable device driver to the Call Vector Table.

Regardless of the success of the InitEnable function, the DevEnable function is called at Shell Initialization time. See DevEnable, and InitEnable for more information.

Video Device Handler Interfaces

The functions that follow are video primitives reserved for use by OS/2 system components. Unexpected results can occur if these functions are started by applications. All of the video device handler functions described below (except for the DLL Initialization function) use the same calling sequence. Parameters are passed to the routines on the stack. The entry point is found in the BVH Call Vector Table at the index of the function number. The calling sequence used to invoke all the routines is as follows:

     PUSH@    OTHER    Environment        ; Environment buffer
     PUSH@    OTHER    ParmBlock          ; Parameter block
     PUSH     DWORD    Function           ; Function number

     CALL     FAR      BVH Routine Entry Point

Environment:

The environment buffer. The format of this buffer is defined by the BVH developer. The selector is a huge selector.

ParmBlock:

A data structure containing all of the parameters of the operation to be performed. The general format of this structure is:

    Length of parameter block in bytes (=NN)  WORD
    Flags                                     WORD

    Bit 0 indicates whether the physical hardware is updated.

        OFF = Initialize only the environment buffer
        ON  = Initialize the environment buffer and the hardware state

    Bits 1 through 15 are reserved and must be OFF.

The length of the parameter block is the total length, including the length field itself. The number in parentheses (=NN) represents the value of this field, if it is a constant. The first flag bit always indicates a background versus foreground state for this function. If the bit is ON, the adapter is actually updated, as it is when an application is in the foreground. If the bit is OFF, only the buffer that is used to shadow the adapter when an application is in the background is actually updated. All bits that are not currently defined as reserved must be OFF.

Function:

The function identifier for this routine. This corresponds to the offset into the Call Vector Table, and can be used to determine the number of parameters on the stack. This is consistent with the existing DDI used by the Presentation Manager interface. All routines are expected to return with AX = 0 if no error was detected. Otherwise, an error code is returned in AX. The following errors are common to all commands:

   ERROR_VIO_INVALID_LENGTH, if the parameter block length is incorrect.
   ERROR_VIO_INVALID_PARMS,  if a reserved flag bit is non-zero, or if
                             the function number does not match the routine.

DevEnable

This function fills the entries in the Call Vector Table for all of the functions supported by this BVH. It is called as a subfunction of the Presentation Manager enable function entry point. To initialize the Call Vector Table for dynamic link libraries:

    PUSH  DWORD   Parameter2    ; Variable parameter 2
    PUSH  DWORD   Parameter1    ; Variable parameter 1
    PUSH  DWORD   Subfunction   ; Enable subfunction

    CALL  FAR     DevEnable

Parameters

Parameter2 for Subfunction=1

A far pointer to this structure:

   DWORD   Flags Pointer
   DWORD   Call Vector Table
   

Flags Pointer

Pointer to where the flags that control calls to the Fill Physical Device Block function go.

Call Vector Table

Pointer to the default dispatch table containing the addresses of the default handler functions and the functions supported by this component. Each entry in the Call Vector Table is the far address of a Video Device Handler function, which must be callable from both Ring 2 and Ring 3. The far address of the nth BVH function is the nth DWORD in the table, beginning with Function 0.

The functions listed below are defined as follows:

000h-0FFh (000-255) Reserved for Presentation Manager interface
100h-11Fh (256-287) Reserved for BVS
120h-12Fh (288-303) Reserved for IBM JAPAN
130h-13Fh (304-319) Reserved for MSKK
100h (256) Function 100h Text Buffer Update
101h (257) Function 101h Initialize Environment
102h (258) Function 102h Save Environment
103h (259) Function 103h Restore Environment
104h (260) Function 104h Query Config Info
105h (261) Function 105h DBCS Display Info
106H (262) Function 106h Query Color Lookup Table
107H (263) Function 107h Set Color Lookup Table
108H (264) Function 108h Query Cursor Info
109H (265) Function 109h Set Cursor Info
10AH (266) Function 10Ah Query Font
10BH (267) Function 10Bh Set Font
10CH (268) Function 10Ch Query Mode
10DH (269) Function 10Dh Set Mode
10EH (270) Function 10Eh Query Palette Registers
10Fh (271) Function 10Fh Set Palette Registers
110H (272) Function 110h Query Physical Buffer
111H (273) Function 111h Free Physical Buffer
112H (274) Function 112h Query Variable Info
113H (275) Function 113h Set Variable Info
114H (276) Function 114h Terminate Environment
115H (277) Function 115h Print Screen
116H (278) Function 116h Write TTY
117H (279) Function 117h Query LVB Info

Parameter1 for Subfunction=1

Far pointer to this structure:

DWORD   Engine Version
DWORD   Count of Table Functions

Engine Version

Version of the Presentation Manager Graphics Engine.

Count of Table Functions

The number of entries in the passed dispatch table. The driver can write only this many entries into the table.

Subfunction

The Presentation Manager enable subfunction number. Its value must be 1 to start the Presentation Manager Fill Logical Device Block subfunction. All pieces of the BVH must support this function. Pieces of the BVH that do not support the Presentation Manager interface do not need to support the other functions. Any function not supported will return PMERR_DEV_FUNC_NOT_INSTALLED.

Remarks

This function is supported by the video dynamic link functions and is called only once for each adapter supported by the physical device driver. A video device handler determines if the display adapter and that which the adapter supports is present. If not present, this function returns an error . Every part of a BVH must successfully initialize the Call Vector Table for that device to be usable by the OS/2 operating system.

InitEnable

This function fills the entries in the Call Vector Table for all of the functions supported by this BVH using only SCREEN$ device driver. It is called with parameters similar to the DevEnable entry point specified in DevEnable, except for the Subfunction parameter.

To initialize the Call Vector Table for dynamic link libraries:

PUSH  DWORD   Parameter2    ; Variable parameter 2
PUSH  DWORD   Parameter1    ; Variable parameter 1
PUSH  DWORD   Subfunction   ; Enable subfunction

CALL  FAR     InitEnable

Parameters

Parameter2 for Subfunction=3

See DevEnable.

Parameter1 for Subfunction=

See DevEnable. Subfunction is the Presentation Manager enable subfunction number. Its value must be 3 to start the Presentation Manager Fill Initialization Device Block subfunction. The default entry point of DevEnable can be overridden by specifying an alternate name in the DEVICE() parameter describing this BVH in the CONFIG.SYS file.

Remarks

This function is called only if video functions are required before Shell Initialization.

The BVH must be able to support the following subfunctions:

100h (256) Function 100h Text Buffer Update
101h (257) Function 101h Initialize Environment
102h (258) Function 102h Save Environment (settable environment only)
103h (259) Function 103h Restore Environment (settable environment only)
104h (260) Function 104h Query Config Info
105h (261) Function 105h DBCS Display Info
108H (264) Function 108h Query Cursor Info
109H (265) Function 109h Set Cursor Info
10CH (268) Function 10Ch Query Mode (80x25 text or equivalent only)
10DH (269) Function 10Dh Set Mode (80x25 text or equivalent only)
112H (274) Function 112h Query Variable Info (code page only)
113H (275) Function 113h Set Variable Info (code page only)

See DevEnable.


Function 100h


Text Buffer Update - Function 100h

This function performs text updates to the logical and physical video buffers. All references to the buffer are made through the text row and column of each cell affected by the called function.

Parmlength 
Length of the data structure in bytes (greater than, or equal to, 26), including the Lengthfield itself. The maximum length is 44 bytes. Values not passed are assumed to be the default values for the environment.
Flags 
Defined as follows:
Bit 0 indicates whether the physical video buffer needs to be updated.
OFF = The physical video buffer must not be updated.
ON = The physical video buffer must be updated.
Bit 1 indicates whether the logical video buffer needs to be updated.
OFF = The logical video buffer may optionally be updated.
ON = The logical video buffer must be updated.
Bit 2 indicates that attribute information in the user buffer is in CGA format and might need to be translated into the format used by the device. This bit is set for VioWrtTTY calls any time that ANSI is active, because

ANSI recognizes only CGA format attributes.

OFF = Use attributes in existing format.
ON = Translation to or from CGA format required.
Bits 3-15 are reserved and must be OFF.
Selector/Offset of the Application Data Area 
Pointer to the application's data area, which provides either the source or the destination for the buffer operation.
Selector/Offset of the Secondary Data Area
Pointer to the additional parameter required by this type of update operation. It is used to define, at most, one cell of information that is used repetitively as filler. This is used only with Index = 3, 4, 5, 6, or 9.
Index 
Defined as follows:
0 = Read Cell Types from (Row,Col) as word of flags:
Bit 0 indicates whether the cell is part of a single or double cell character.
OFF = The cell represents a single cell character.
ON = The cell represents part of a double cell character. Bit 1 is examined for more information.
Bit 1 indicates whether the cell is a trailing cell of a double cell character.
OFF = The cell represents the leading or only cell of a character.
ON = The cell represents the trailing cell of a double cell character.
Bits 2 thru 15 are reserved and must be OFF.
 1 = Read Characters from (Row,Col)
 2 = Read Cells from (Row,Col)
 3 = Scroll (Row,Col) through (Row2,Col2) Up
 4 = Scroll (Row,Col) through (Row2,Col2) Down
 5 = Scroll (Row,Col) through (Row2,Col2) Left
 6 = Scroll (Row,Col) through (Row2,Col2) Right
 7 = Write Cells to (Row,Col)
 8 = Write Characters to (Row,Col)
 9 = Write Characters with Constant Attr to (Row,Col)
10 = Write Repeated Character to (Row,Col)
11 = Write Repeated Attribute to (Row,Col)
12 = Write Repeated Cell to (Row,Col)
13 = Copy LVB Rect to PVB
Starting Row
Defines the text location (row) in the Video Buffer at which the update is to be started. For Function 13, this is the upper-left corner of the rectangle to be written.
Starting Column 
Defines the text location (column) in the Video Buffer at which the update is to be started. For Function 13, this is the upper-left corner of the rectangle to be written.
Secondary Row 
Defines the text location (row) in the Video Buffer to which cells will be moved. This is used only when moving cells from one location to another ( Index=3-6). For Function 13, this is the lower-right corner of the rectangle to be written.
Secondary Column 
Defines the text location (column) in the Video Buffer to which cells will be moved. This is used only when moving cells from one location to another (Index=3-6). For Function 13, this is the lower-right corner of the rectangle to be written.
Repeat Factor 
Repeat factor used when updating the buffer. It represents the number of character cells to be updated, or the number of rows or columns to be scrolled. This is used for both input and output.
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.
TouchXLeft 
The X-coordinate of the upper-left corner of the tightest rectangle that circumscribes the cells touched by the current function. If no cells were touched (as in a Read), -1 is returned. Collectively, this field and the next three fields form an area of influence for the call. This field is returned by the BVH.
TouchYTop 
The Y-coordinate of the upper-left corner of the tightest rectangle that circumscribes the cells touched by the current function. If no cells were touched, -1 is returned. This field is returned by the BVH.
TouchXRight 
The X-coordinate of the lower-right corner of the tightest rectangle that circumscribes the cells touched by the current function. If no cells were touched, -1 is returned. This field is returned by the BVH.
TouchYBottom 
The Y-coordinate of the lower-right corner of the tightest rectangle that circumscribes the cells touched by the current function. If no cells were touched, -1 is returned. This field is returned by the BVH.
LVBRowOff 
The row offset of the upper-left corner of the LVB in PVB coordinates. All reads, writes, and scrolls are done in PVB coordinates.
LVBColOff 
The column offset of the upper-left corner of the LVB in PVB coordinates. All reads, writes, and scrolls are done in PVB coordinates.
LVBWidth 
The width of the LVB in cells. Must be greater than 0.
LVBHeight 
The height of the LVB in cells. Must be greater than 0.
LVBFormatID 
The format ID of the LVB. If this value and attribute count are both 0, the Format ID and attribute count for the current mode are used.
LVBAttrCount 
The attribute count for the LVB.

Function 100h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Selector/Offset of the Application Data Area DWORD
Selector/Offset of the Secondary Data Area DWORD
Index WORD
Starting Row WORD
Starting Column WORD
Secondary Row WORD
Secondary Column WORD
Repeat Factor WORD
Logical Buffer Selector WORD
TouchXLeft WORD
TouchYTop WORD
TouchXRight WORD
TouchYBottom WORD
LVBRowOff WORD
LVBColOff WORD
LVBWidth WORD
LVBHeight WORD
LVBFormatID BYTE
LVBAttrCount BYTE

Function 100h - Returns

The Text Buffer Update routine returns with AX = 0, if no error was detected. Otherwise, the following error codes are returned in AX:

ERROR_VIO_COL, if an invalid column number was specified
ERROR_VIO_INVALID_LENGTH, if the ParmLength was incorrect
ERROR_VIO_INVALID_PARMS, if the Index was incorrect
ERROR_VIO_MODE, if updates are not supported in the current video mode
ERROR_VIO_ROW, if an invalid row number was specified.

Function 100h - Remarks

The Touchxxxx fields circumscribe the area of the LVB, or PVB, for a rectangle that was potentially changed by the given operation. For example, a Write that included the cells (10,12) to (79,12), (0,13) to (79,13), and (0,14) to (8,14) returns TouchXLeft=0, TouchYTop=12, TouchXRight=79, and TouchYBottom=14. Any new functions added to the BVH interface that can affect the data in the PVB or LVB must include a return area for the rectangle of the video buffer that was affected by the given call.

The LVBxxxx fields indicate that an LVB can differ from the normal LVB format. The information about the LVB is taken from these fields, if they are included. Notice that these fields allow an LVB to begin at a location other than (0,0) and allow LVBs of different row and column dimensions.

Function 101h

Initialize Environment - Function 101h

This function causes the Environment Buffer and the video adapter (optional) to be initialized.

Parmlength 
Length of parameter block in bytes (=6) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Initialize only the environment buffer.
ON = Initialize the environment buffer and the hardware state.
Bit 1 indicates whether the 3xBox is being initialized.
OFF = The 3xBox is not being initialized.
ON = The 3xBox is being initialized.
Bits 2 thru 15 are reserved and must be OFF.
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.

Function 101h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Logical Buffer Selector WORD

Function 101h - Returns

This routine always returns with AX = 0.

Function 101h - Remarks

It must be possible to call Restore Environment before Save Environment.

Function 102h

Save Environment - Function 102h

This function is used to save all aspects of the video adapter, including the hardware state and the video buffers.

Parmlength 
Length of parameter block in bytes (=6) passed on input.
Flags 
Defined as follows:
Bit 0 is reserved and must be Off.
Bit 1 indicates whether hardware state (mode, CLUT, everything except the buffer) is saved.
OFF = The hardware state is not saved.
ON = The hardware state is saved.
Bit 2 indicates whether the physical display is fully saved for session switching.
OFF = The physical display is not fully saved.
ON = The physical display is fully saved.
Bit 3 indicates whether the physical display is partially saved for pop-ups.
OFF = The physical display is not partially saved.
ON = The physical display is partially saved.
Bits 4 thru 15 are reserved and must be OFF.</pre>
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.

Function 102h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Logical Buffer Selector WORD

Function 102h - Returns

The Save Environment routine returns with AX=0 if it can successfully save the environment to the Environment Block and the Logical Video Buffer. Otherwise, it returns with AX=ERROR_VIO_MODE.

Function 102h - Remarks

Bits 2 and 3 are mutually exclusive. If both are specified, bit 3 will be ignored. Bit 4 is used in combination with bits 2 and 3. The code and data segments referenced or accessed to perform the functions selected by bits 1 and 3 must be locked during device driver initialization. The format of the data saved in the segments passed as input is determined by the device handler.

Partial saves are started on VIO and hard error pop-ups. Pop-ups appear on the primary display configuration. The device driver must save whatever portion of the physical display buffer that is overlaid by the pop-up. To display a pop-up, OS/2 2.1 switches to the highest resolution 80 x 25 text mode supported by the primary display configuration (mode 3 or 7, whichever is listed first in the list of modes supported by the display configuration). Alternatively, if a device driver's physical display buffer is not overlaid by a pop-up, the physical device driver returns zero for partial save size.

When a hard error pop-up occurs before a VIO pop-up has cleared, the Save Environment function is called twice before the Restore Environment is called. Therefore, the device handler must be prepared to handle both a partial save of a graphics mode and a full save of the text mode of the user pop-up.

OS/2 allocates the buffer in which the physical display buffer is saved by using DosAllocHuge. The selector to the Data Packet addresses the first of n segments in which the physical display buffer is saved. (The offset to the Data Packet should be ignored.) The selector to the second segment can be calculated by adding the DosAllocHuge increment to the first selector value. The third selector can similarly be calculated by adding the DosAllocHuge increment to the second selector value, and so forth. Enough selectors are allocated to meet the full/partial buffer requirement specified by the physical device driver. The selectors each address 64KB except the last selector, which addresses the remainder.

Function 103h

Restore Environment - Function 103h

This function is used to restore all aspects of the video adapter, including the hardware state and the video buffers.

Parmlength 
Length of parameter block in bytes (=6) passed on input.
Flags 
Defined as follows:
Bit 0 is reserved and must be Off.
Bit 1 indicates whether hardware state (mode, CLUT, everything except the buffer) is saved.
OFF = The hardware state is not restored.
ON = The hardware state is restored.
Bit 2 indicates whether the physical display is fully restored for session switching.
OFF = The physical display is not fully restored.
ON = The physical display is fully restored.
Bit 3 indicates whether the physical display is partially restored for pop-ups.
OFF = The physical display is not partially restored.
ON = The physical display is partially restored.
Bits 4 thru 15 are reserved and must be OFF.
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.

Function 103h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Logical Buffer Selector WORD

Function 103h - Returns

The Restore Environment routine returns with AX = 0 if it can successfully restore the environment to the Environment Block and the Logical Video Buffer. Otherwise, it returns with AX = ERROR_VIO_MODE. See Function 102h for more information.

Function 104h


Query Config Info - Function 104h

This function returns all of the information necessary to identify the current video adapter and display.

Parmlength 
Length of parameter block in bytes (=8) passed on input.
Flags 
Must be zero.

Function 104h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD

Function 104h - Returns

This function returns with AX = ERROR_VIO_INVALID_LENGTH only if the Length specified is less than 2.

Function 104h - Remarks

The Environment Buffer is not used by this function. The Environment Buffer address is passed as a DWORD of zero. If the Length specified in the Config Data is larger than the maximum possible length, or if the Length is specified as 2 (the length of Length field itself), it is replaced by the largest valid length.

Function 105h


DBCS Display Info - Function 105h

This function returns various forms of DBCS information used by the display.

Parmlength 
Length of parameter block in bytes. If Length is specified as 2, only the maximum length of the parameter block is returned in the length field. If the length is not 2, it defines the maximum amount of data returned.
Flags
Must be zero.
DBCS Table Length
Length of double cell character table.
DBCS Table Offset
Offset of double-cell character table, which consists of WORD pairs that define the low and high limits (inclusive) of ranges of double-cell characters.

Function 105h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
DBCS Table Length WORD
DBCS Table Offset WORD

Function 105h - Returns

This function is used to get the DBCS display information associated with the given environment buffer, and returns with AX = ERROR_VIO_INVALID_ LENGTH if the Length specified is less than 2 or the buffer was too short to return all of the DBCS display information. Otherwise, Query DBCS Display Info returns with AX = 0.

Function 106h

Query Color Lookup Table - Function 106h

This function reads the definitions of the colors from the Color Lookup Table.

Parmlength 
Length of parameter block in bytes (=12) passed on input.
Flags
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Return data from the environment buffer only.
ON = Read the hardware to update the environment buffer before returning the requested data.
Bits 1-15 are reserved and must be OFF.
Color Lookup Table Far Address 
Far address of Color Lookup Table. The Table format is device-dependent. Three-byte table entries are returned for the VGA. Each table entry contains a red, green, and blue color index, respectively.
Index 
Index of the first table entry to get.
Table Entry Quantity 
Number of table entries to get. Three-byte table entries are returned for the VGA. Each table entry contains a red, green, and blue color index, respectively.

Function 106h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Color Lookup Table Far Address DWORD
Index WORD
Table Entry Quantity WORD

Function 106h - Returns

This function returns with AX = 0 if it can successfully get all of the requested registers from the Color Lookup Table. Otherwise, this routine returns with AX = ERROR_VIO_INVALID_PARMS if an invalid color register was requested, or AX = ERROR_VIO_INVALID_LENGTH if too many registers were requested.

Function 107h

Set Color Lookup Table - Function 107h

This function loads the definitions of the colors from the Color Lookup Table.

Parmlength 
Length of parameter block in bytes (=12) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Update only the environment buffer.
ON = Update the environment buffer and the hardware state.
Bits 1-15 are reserved and must be OFF.
Color Lookup Table Far Address 
Far address of Color Lookup Table. The Table format is device-dependent. The VGA format has three bytes containing the red, green and blue indices, respectively, for each color being set.
Index 
Index of the first table entry to set.
Table Entry Quantity 
Number of table entries to set.

Function 107h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Color Lookup Table Far Address DWORD
Index WORD
Table Entry Quantity WORD

Function 107h - Returns

This function returns with AX = 0 if it can successfully set all of the registers in the Color Lookup Table. Otherwise, it returns with AX = ERROR_VIO_INVALID_PARMS if an invalid color register was requested, or AX = ERROR_VIO_INVALID_LENGTH if too many registers were requested.

Function 108h

Query Cursor Info - Function 108h

This function returns all of the information related to the cursor.

Parmlength 
Length of parameter block in bytes (=16) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Return data from the environment buffer only.
ON = Read the hardware to update the environment buffer before returning the requested data.
The remaining flags select the information to be returned:
Bit 1 selects cursor position.
Bit 2 selects cursor type.
Bits 3-15 are reserved and must be Off.
Row 
0 is the top row.
Column 
0 is the left column.
Top Cursor Scan Line 
If n scan lines, 0 is top scan line and n-1 is bottom scan line.
Bottom Cursor Scan Line 
If n scan lines, 0 is top scan line and n-1 is bottom scan line.
Cursor Width 
Cursor width in columns, if text mode; in pels, if graphics mode.
Cursor Attribute 
Cursor attribute: -1 = hidden, if text mode; other values = color attribute, if graphics mode.

Function 108h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Row WORD
Column WORD
Top Cursor Scan Line WORD
Bottom Cursor Scan Line WORD
Cursor Width WORD
Cursor Attribute WORD

Function 108h - Returns

This function returns with AX = 0 if it can successfully get all of the cursor information requested. Otherwise, it returns with AX = ERROR_VIO_INVALID_PARMS.

Function 109h

Set Cursor Info - Function 109h

This function sets all of the information related to the cursor.

Parmlength
Length of parameter block in bytes (=16) passed on input.
Flags
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Update only the environment buffer.
ON = Update the environment buffer and the hardware state.
The remaining flags select the options to be set:
Bit 1 selects cursor position.
Bit 2 selects cursor type.
Bits 3-15 are reserved and must be OFF.
Row 
0 is the top row.
Column 
0 is the left column.
Top Cursor Scan Line
If n scan lines, 0 is top scan line and n-1 is bottom scan line.
Bottom Cursor Scan Line
If n scan lines, 0 is top scan line and n-1 is bottom scan line.
Cursor Width
Cursor width in columns, if text mode; in pels, if graphics mode.
Cursor Attribute 
Cursor attribute: -1 = hidden, if text mode; other values = color attribute, if graphics mode.

Function 109h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Row WORD
Column WORD
Top Cursor Scan Line WORD
Bottom Cursor Scan Line WORD
Cursor Width WORD
Cursor Attribute WORD

Function 109h - Returns

This function returns with AX = 0 if it can successfully set all of the cursor information requested. Otherwise, it returns with AX equal to:

  • ERROR_VIO_MODE if it cannot support the function in the current mode
  • ERROR_VIO_ROW if the row number is out of range
  • ERROR_VIO_COL if the column number is out of range

Function 10Ah

Query Font - Function 10Ah

This function returns the current active font or a selected font for the current code page. The format of the font definition is determined by the type of adapter.

Parmlength 
Length of parameter block in bytes (=14) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Return data from the environment buffer only.
ON = Read the hardware to update the environment buffer before returning the requested data.
Bit 1 indicates whether a specific font is to be returned instead of the current font.
OFF = Return the current font.
ON = Return the selected font for the current code page. Setting this flag indicates that the pel columns and rows are used as input to select the font.
Bits 2-15 are reserved and must be OFF.
Font Buffer Far Address
Data area in which the font definition is returned.
Data Area Length 
Length of data area in which font table is returned.
Pel Columns 
Pel columns.
Pel Rows
Pel rows.

Function 10Ah - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Font Buffer Far Address DWORD
Data Area Length WORD
Pel Columns WORD
Pel Rows WORD

Function 10Ah - Returns

If the Length is specified as 0, no font is returned. Instead, the Length field returns the size needed to hold the font. Query Font returns with AX = 0 if it can successfully read the font. Otherwise, it returns with AX = ERROR_VIO_INVALID_PARMS.

Function 10Bh

Set Font - Function 10Bh

This function sends a user font definition to the device handler. If the font is appropriate for the current mode, it is loaded into the adapter. If not, it is saved for possible use on subsequent calls to SetMode. The format of the font definition is determined by the type of adapter.

Parmlength
Length of parameter block in bytes (=14) passed on input.
Flags
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Update only the environment buffer.
ON = Update the environment buffer and the hardware state.
Bits 1-15 are reserved and must be OFF.
Font Buffer Far Address 
Far address of the font buffer containing the font set in compact form.
Data Area Length
Length of data area containing the font table to be set.
Pel Columns
Pel columns.
Pel Rows
Pel rows.

Function 10Bh - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Font Buffer Far Address DWORD
Data Area Length WORD
Pel Columns WORD
Pel Rows WORD

Function 10Bh - Returns

This function returns with AX = 0 if it can successfully load the font. Otherwise, it returns with AX = ERROR_VIO_INVALID_PARMS.

Function 10Ch

Query Mode - Function 10Ch

This function returns all of the information pertaining to the current video mode.

Parmlength
Length of parameter block in bytes (=8) passed on input.
Flags
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Return data from the environment buffer only.
ON = Read the hardware to update the environment buffer before returning the requested data.
Bits 1-15 are reserved and must be OFF.
Mode Data Structure Far Address
Far Address of the Mode data structure defined by VioGetMode.

Function 10Ch - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Mode Data Structure Far Address DWORD

Function 10Ch - Returns

If the Length specified in the Config Data is larger than the maximum possible length or if the Length is specified as 2, it is replaced by the largest valid length. This function returns with AX = ERROR_VIO_INVALID_LENGTH only if the Length specified is less than 2.

Function 10Dh

Set Mode - Function 10Dh

This function sets the video mode of the video adapter. For text modes, it considers not only what display characteristics it can support but also what ROM, code page, and user-defined fonts it has available.

Datalength 
Length of the data structure in bytes, including Length itself (=8).
Flags
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Update only the environment buffer.
ON = Update the environment buffer and the hardware state.
Bit 1 indicates whether the mode is changed or only validated.
OFF = Perform normal mode setting.
ON = Perform only mode validation.
Bits 2-15 are reserved and must be OFF.
Mode Data Structure Far Address 
Far Address of the Mode data structure defined by VioSetMode.

Function 10Dh - Parameter Packet Format

Field Length
Datalength WORD
Flags WORD
Mode Data Structure Far Address DWORD

Function 10Dh - Returns

Set Mode returns with AX = 0 if it can set the requested mode. Otherwise, it returns with AX = ERROR_VIO_MODE.

Function 10Dh - Remarks

This function must validate the mode data without using the environment buffer, because it might not have been initialized or might not be valid for this device. This function implicitly initializes the environment buffer if it has not already been done.

Function 10Eh

Query Palette Registers - Function 10Eh

This function queries the relationship between the text attributes and the color registers.

Datalength 
Length of parameter block in bytes (=12) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Return data from the environment buffer only.
ON = Read the hardware to update the environment buffer before returning the requested data.
Bits 1-15 are reserved and must be OFF.
Palette Buffer Far Address 
Data area where a 1-WORD entry for each register containing its color value is returned.
Palette Register Index
Index of first palette register to get.
Register Quantity
Number of registers to return.

Function 10Eh - Parameter Packet Format

Field Length
Datalength WORD
Flags WORD
Palette Buffer Far Address DWORD
Palette Register Index WORD
Register Quantity WORD

Function 10Eh - Returns

This function returns with AX = 0 if it can successfully get all of the requested palette registers. Otherwise, it returns with AX = ERROR_VIO_ INVALID_PARMS if an invalid color register was requested, or AX = ERROR_VIO _INVALID_LENGTH if too many registers were requested.

Function 10Fh

Set Palette Registers - Function 10Fh

This function defines the relationship between the text attributes and the color registers.

Parmlength 
Length of parameter block in bytes (=12) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Update only the environment buffer.
ON = Update the environment buffer and the hardware state.
Bits 1-15 are reserved and must be OFF.
Palette Buffer Far Address 
Far address of palette register buffer. Data area with 1 WORD, containing the color value for each register set.
Palette Register Index 
Index of first palette register to set. Data area with 1 WORD, containing the color value for each register set.
Register Quantity 
Number of registers to set.

Function 10Fh - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Palette Buffer Far Address DWORD
Palette Register Index WORD
Register Quantity WORD

Function 10Fh - Returns

This function returns with AX = 0 if it can successfully set all of the requested palette registers. Otherwise, it returns with AX = ERROR_VIO_ INVALID_PARMS if an invalid color register was requested, or AX = ERROR_VIO _INVALID_LENGTH if too many registers were requested.

Function 110h

Query Physical Buffer - Function 110h

This function returns an LDT selector that can be used to access the physical video buffer. The current physical video buffer is returned unless a specific address range is requested.

Parmlength 
Length of parameter block in bytes (=12) passed on input.
Flags 
Must be zero.
Query Physical Buffer Far Address 
Far Address of the Query Physical Buffer data structure defined by VioGetPhysBuf.

Function 110h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Query Physical Buffer Far Address DWORD

Function 110h - Returns

Query Physical Buffer returns with AX = 0 if it can successfully allocate the LDT selector. Otherwise, it returns with AX set by the PhysToUVirtdevice helper function or with AX = ERROR_VIO_INVALID_PARMS if the requested buffer resides outside the valid range for the device.

Function 110h - Remarks

If the physical display buffer address and length passed on input are 0, this subfunction returns an LDT selector, that corresponds to the current mode.

A physical video device driver must provide Read/Write access to the physical address range where the physical display buffer is located. The physical device driver must provide Read-only access to the physical address range where the ROM fonts are located. If the physical address passed on input is not within the physical display buffer or ROM font ranges, an error is returned.

Function 111h


Free Physical Buffer - Function 111h

This function deallocates an LDT selector that was acquired by a call to the Query Physical Buffer routine.

Parmlength 
Length of parameter block in bytes (=6) passed on input.
Flags 
Must be zero.
LDT Selector 
LDT Selector.

Function 111h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
LDT Selector DWORD

Function 111h - Returns

This function always returns with AX = 0.

Function 112h


Query Variable Info - Function 112h

This function reads various minor features of the video adapter, including the blink state, border color, underscore line, and scrollable rectangle of the screen.

Parmlength 
Length of parameter block in bytes (=26) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Return data from the environment buffer only.
ON = Read the hardware to update the environment buffer before returning the requested data.
The remaining flags select the information to be returned:
Bit 1 selects blink versus background color.
Bit 2 selects overscan (border) color.
Bit 3 selects scan line for underscore.
Bit 4 selects video enable.
Bit 5 selects the display mask.
Bit 6 selects code page.
Bit 7 forces a code page set (used with 6).
Bit 8 gets the scrollable rectangle.
Bits 9-15 are reserved and must be OFF.
Blink/Background Intensity 
Blink versus background intensity:
0 = blink.
1 = background intensity.
Overscan (border) Color 
Overscan (border) Color.
Scan Line
Scan line for underscore (0-31); 32 = no underscore.
Video Enable 
Video enable: 0 = OFF and 1 = ON. OFF means off until the physical device driver is told to turn it back on. If the video signal is turned off and then the mode is set, the signal must remain off.
Display Mask 
Display mask:
   bit 0  = plane 0
     ?         ?
     ?         ?
     ?         ?
   bit 31 = plane 31

   bit state = 0, plane disabled for display.
   bit state = 1, plane enabled for display.

   (Planes disabled for display result in 0 to palette.)
Code Page
Code Page.
Scrollable Rectangle - Left
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Scrollable Rectangle - Top 
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Scrollable Rectangle - Right 
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Scrollable Rectangle - Bottom 
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Screen Rows 
The number of text rows in the current mode.
Screen Columns 
The number of text columns in the current mode.

Function 112h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Blink/Background Intensity WORD
Overscan (border) Color WORD
Scan Line WORD
Video Enable WORD
Display Mask DWORD
Code Page WORD
Scrollable Rectangle - Left WORD
Scrollable Rectangle - Top WORD
Scrollable Rectangle - Right WORD
Scrollable Rectangle - Bottom WORD
Screen Rows WORD
Screen Columns WORD

Function 112h - Returns

Query Variable Info returns with AX = 0 if it can successfully get the selected variable information. Otherwise, it returns with AX = ERROR_VIO_ INVALID_PARMS.

Set Variable Info - Function 113h


Set Variable Info - Function 113h

This function sets the minor features of the video adapter, including the blink state, border color, underscore line, and scrollable rectangle of the screen.

Parmlength
Length of parameter block in bytes (=26) passed on input.
Flags
Defined as follows:
Bit 0 indicates whether the physical hardware is updated.
OFF = Update only the environment buffer.
ON = Update the environment buffer and the hardware state.
The remaining flags select the information to be set:
Bit 1 selects blink versus background color.
Bit 2 selects overscan (border) color.
Bit 3 selects scan line for underscore.
Bit 4 selects video enable.
Bit 5 selects the display mask.
Bit 6 selects code page.
Bit 7 forces a code page set (used with 6).
Bit 8 gets the scrollable rectangle.
Bits 9-15 are reserved and must be OFF.
Blink/Background Intensity 
Blink versus background intensity:
0 = blink.
1 = background intensity.
Overscan (border) Color 
Overscan (border) Color.
Scan Line 
Scan line for underscore (0-31); 32 = no underscore.
Video Enable 
Video enable: 0 = OFF and 1 = ON. OFF means off until the physical device driver is told to turn it back on. If the video signal is turned off and then the mode is set, the signal must remain off.
Display Mask 
Display mask:
   bit 0  = plane 0
     ?         ?
     ?         ?
     ?         ?
   bit 31 = plane 31

   bit state = 0, plane disabled for display.
   bit state = 1, plane enabled for display.

   (Planes disabled for display result in 0 to palette.)
Code Page 
Code Page.
Scrollable Rectangle - Left
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Scrollable Rectangle - Top
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Scrollable Rectangle - Right
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Scrollable Rectangle - Bottom
The scrollable rectangle fields indicate the area of the screen that can scroll during scroll and write TTY operations.
Screen Rows
The number of text rows in the current mode. Reserved (0).
Screen Columns
The number of text columns in the current mode. Reserved (0).

Function 113h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Blink/Background Intensity WORD
Overscan (border) Color WORD
Scan Line WORD
Video Enable WORD
Display Mask DWORD
Code Page WORD
Scrollable Rectangle - Left WORD
Scrollable Rectangle - Top WORD
Scrollable Rectangle - Right WORD
Scrollable Rectangle - Bottom WORD
Screen Rows WORD
Screen Columns WORD

Function 113h - Returns

Set Variable Info returns with AX = 0 if it can successfully set the selected variable information. Otherwise, it returns with AX = ERROR_VIO_ INVALID_PARMS.

Function 113h - Remarks

There are two types of code page sets. The first code page set allows a code page to be set while the mode of the display (as used by Function 10Dh ) remains the same. The other type of code page set causes a change in the display mode. This occurs when switching between DBCS and non-DBCS code pages.

If bit 6 of the flags WORD is set and bit 7 is clear, the code page is set when the adapter can use the code page without changing from DBCS mode to SBCS mode, or vice versa. The mode should be changed if both bits 6 and 7 of the flags WORD are set, and the code page is used when the mode is changed from SBCS mode to DBCS mode. Bit 7 is ignored if bit 6 is not set. This applies only to text modes. Graphics modes are not set to text modes by forcing a code page.

The BVH need not support any scrollable region other than the entire display area. The adapter may support any scrollable rectangle up to the size of the entire screen. All coordinates are in text display cells. This scrollable rectangle data is undefined for graphics modes.

Function 114h


Terminate Environment - Function 114h

This function is used to notify the BVH that the environment is about to be freed so that any required cleanup can be performed by the BVH. If no Terminate Environment processing is required, this function can be omitted. PMERR_DEV_FUNC_NOT_INSTALLED is then returned in AX, but it is ignored by the video subsystem.

Parmlength 
Length of parameter block in bytes (=6) passed on input.
Flags 
Reserved, must be off.
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.

Function 114h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Logical Buffer Selector WORD

Function 114h - Returns

None.

Function 115h

Print Screen - Function 115h

This function causes the contents of the current screen to be written to the printer handle provided. BVS provides a default routine that provides the same level of support as previous versions if the vector is not replaced.

Parmlength 
Length of parameter block in bytes (=8) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical video buffer should be printed.
OFF = Print only the contents of the logical video buffer.
ON = Print the contents of the physical video buffer, if appropriate.
Bits 1-15 are reserved and must be OFF.</pre>
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.
Print Device Handle 
Print Device Handle. File handle of the print device to be used.

Function 115h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Logical Buffer Selector WORD
Print Device Handle WORD

Function 115h - Returns

None.

Function 116h

Write TTY - Function 116h

This function performs the functions of the call to VioWrtTTY. BVS provides a default routine that provides the same level of support as previous versions if the vector is not replaced.

Parmlength 
Length of parameter block in bytes (=14) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical video buffer needs to be updated.
OFF = The physical video buffer must not be updated.
ON = The physical video buffer must be updated.
Bit 1 indicates whether the logical video buffer needs to be updated.
OFF = The logical video buffer can optionally be updated.
ON = The logical video buffer must be updated.
Bit 2 indicates whether ANSI is active.
OFF = ANSI is not active. Escape sequences should be considered as text data.
ON = ANSI is active. Escape sequences must be handled locally or passed to the default routine in BVS through device chaining.
Bit 3 indicates whether Ctrl_PrtSc is active.
OFF = Ctrl_PrtSc is not active.
ON = Ctrl_PrtSc is active. Characters need to be echoed to the printer locally or by the default routine in BVS through device chaining.
Bits 4-15 are reserved and must be OFF.
Logical Buffer Selector 
Selector used for the beginning of the logical video buffer. This selector is a huge selector with a maximum size of 1MB.
Character String Far Address 
Far Address of character string to be written.
Character String Length 
Length of character string to be written.
Print Device Handle 
Print Device Handle. The file handle of the print device used for Ctrl_ PrtSc.

Function 116h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
Logical Buffer Selector WORD
Character String Far Address DWORD
Character String Length DWORD
Print Device Handle WORD

Function 116h - Returns

None.

Function 117h

Query LVB Info - Function 117h

This function returns information associated with the LVB, such as the allocation size and default attribute for a specified LVB.

Parmlength 
Length of parameter block in bytes (=20) passed on input.
Flags 
Defined as follows:
Bit 0 indicates whether the physical hardware is to be read.
OFF = Read from the environment buffer.
ON = Read from the current state of the hardware state.
Bits 1-15 are reserved and must be OFF.
LVB Format ID 
Format ID for LVB. If this and the attribute count are both 0, the current mode values are used.
LVB Attribute Count 
Attribute Count for the LVB. If this and the format ID are both 0, the current mode values are used.
LVB Width 
LVB Width in cells.
LVB Height 
LVB Height in cells.
LVB Allocation Size 
Allocation size of the LVB is returned here.
Attribute Return Buffer Size 
Size of the default attribute return buffer.
Attribute Return Buffer Pointer 
Pointer to the default attribute return buffer (passed). The default attribute is returned if the buffer is large enough. If this value is 0, the attribute is not returned.

Function 117h - Parameter Packet Format

Field Length
Parmlength WORD
Flags WORD
LVB Format ID BYTE
LVB Attribute Count BYTE
LVB Width WORD
LVB Height WORD
LVB Allocation Size DWORD
Attribute Return Buffer Size WORD
Attribute Return Buffer Pointer DWORD

Function 117h - Returns

This function returns with AX = 0 if it can successfully calculate the LVB size and return the attribute information. Otherwise, it returns with AX = ERROR_VIO_INVALID_PARMS.

Level 0 Physical Device Driver Interfaces

The strategy portion of the Level 0 physical device drivers that can be a component of any video device handler is called to handle I/O requests through a request packet interface with the OS/2 kernel. The strategy routine executes at task-time as a result of an application VIO request. The strategy routine is called with ES:BX pointing to the request packet (the pointer is valid in both a DOS session and an OS/2 session). Only three command codes (passed in the request packet) are required to be supported by a video device driver. For any other command code the physical device driver does not support, the physical video device driver must return Unsupported Command and Done in the request packet status field.

The following are the physical device driver commands that are supported by the physical video device driver (the command codes are in parentheses):

INIT (00h) - Initialize the Device

On entry, the request block contains the following fields as inputs to the physical video device driver:

Pointer to the DevHlp entry point
Pointer to the INIT arguments

On exit, the physical video device driver sets the first pointer to the offsets of the code and data segments to release code and data needed only by the initialization routine. The second pointer is set to 0. If initialization is successful, the request packet status field is set to indicate No Error and Done; otherwise, the status is set to General Failure.

The physical video device driver can perform the following initialization:

Obtain the DevHlp address from the request packet.
Verify that the display adapter and the display that it supports are present. If not, it can fail initialization.

OPEN (0Dh) - Open the Device

This service routine does nothing but return with No Error status.

GENERIC IOCtl (10h) - Send I/O Requests to the Device

On entry, the request packet has the IOCtl category code and function code set. The parameter buffer and the data buffer addresses are set as virtual addresses. The physical video device driver performs the physical device driver initialization, when requested.

Physical Device Driver Initialization

The IOCtl described below supports the same class of functions as the Presentation Manager dynamic link enable entry point. It is called to fill in the Call Vector Table for the BVH. The call returns an error if the physical device driver detects that the adapter is not present.

Category 3 
Function 73h
Purpose 
To initialize the Call Vector Table.
Parameter Block Format 
None.
Data Packet Format 
DWORD Subfunction
DWORD Parameter1
DWORD Parameter2
WORD ReturnCode

Subfunction

The Presentation Manager enables the subfunction number. Its value must be 1 to start the Presentation Manager Fill Logical Device Block subfunction. All pieces of the BVH must support this function. Pieces of the BVH that do not support the Presentation Manager interface do not need to support the other functions. Any function not supported should return PMERR_DEV_FUNC_NOT_INSTALLED.

Parameter1 for Subfunction = 1

Far pointer to this structure:

DWORD Engine Version
DWORD Count of Table Functions

Engine Version Version of the Presentation Manager Graphics Engine

Count of Table Functions Number of entries in the passed dispatch table. The physical device driver can only write this many entries into the table.

Parameter2 for Subfunction=1

Far pointer to this structure:

DWORD Flags Pointer
DWORD Call Vector Table

Flags Pointer Pointer to where the flags controlling calls to the Fill Physical Device Block function go.

Call Vector Table Pointer to the default dispatch table containing the addresses of the default handler functions and the functions supported by this component. Each entry in the Call Vector Table is the far address of a Video Device Handler function, which must be callable from Ring 3. The address of the nth BVH function is the nth DWORD in the table, beginning with Function 0. Refer to the DLL Initialization function for a description of the function numbers.

Remarks

This function is supported by the video device drivers and is called only once for each adapter to be supported by the BVH. A video device handler should determine if the display adapter and that which it supports is present. If not present, this function must return an error. Every part of a BVH must successfully initialize the Call Vector Table for that device to be used by OS/2.

EGA.SYS and INT 2Fh Screen Switch Notification

For some DOS EGA applications, OS/2 is not able to switch from a DOS session to an OS/2 session and then back again. Upon return to the DOS application, the screen will be incorrect. The DOS EGA applications that do not run successfully are:

  • Applications that download fonts into a character generator block other than Block 0. Character Generator Block 0 is supported.
  • Graphic mode applications that use more than one display page.
  • Advanced graphics mode applications that write directly to the registers on the EGA adapter.

To supplement OS/2 screen switching support, a DOS application can be written to use the EGA register interface. Alternatively, a DOS application can be notified on a screen switch through multiplex interrupt 2Fh, AH = 40h. These two mechanisms are described in the following sections.

Note: On an IBM PS/2 personal computer the registers on the adapter are both readable and writable. For these configurations, OS/2 reads and saves the registers on a screen switch away from a DOS session, and restores the registers upon return to a DOS session.

For configurations including the IBM PS/2 Display Adapter 8514/A when the 8514/A display adapter is in an advanced function mode, the OS/2 operating system does not save the physical display buffer when switching away from a DOS session. Therefore, end users are cautioned to complete any 8514/A advanced function mode application before switching to OS/2 mode.

EGA.SYS Device Driver

EGA.SYS is a physical device driver that provides support for the EGA register interface in a DOS session. To support advanced graphics modes D, E, F, and 10 in a DOS session, the Mouse Pointer Draw device driver must save or restore the EGA registers. Because the EGA registers are not readable, this can be done only if the application assists in setting the registers initially. Rather than performing I/O directly to the registers on the adapter, the application sets the registers through the EGA register interface.

EGA Register Interface

The EGA register interface is a library of ten functions supported for a DOS session, advanced graphics applications (modes D, E, F, and 10). These functions do the following:

  • Read from, or write to, one or more of the EGA write-only registers
  • Define default values for the EGA write-only registers, reset the EGA registers to these default values, or return the default values
  • Check whether the EGA register interface is present and, if so, return its version number.

When the application uses the EGA register interface, OS/2 2.1 maintains a backup copy or shadows how the EGA registers are set. Then, if the operator switches away from (and later returns to) the application, the registers are restored properly. It is not necessary to use the EGA register interface to set the mode, color palette, or palette registers. Instead, use ROM BIOS function INT 10h with AH = 00h, 0Bh, or 10h, respectively.

Calling The EGA Register Interface

To call EGA register interface functions from an assembly language program, the following actions must be performed:

  1. Load the registers with the required parameter values
  2. Execute software interrupt 10h.

Values returned by the EGA register interface functions are placed in registers.

EGA Register Interface Restrictions

A list of areas where restrictions apply for the EGA Register Interface are shown below:

Functions not supported
?Attribute Controller registers
Sequencer Memory Mode register
Input Status registers
Graphics Controller Miscellaneous register

Functions Not Supported

Multiple display pages in graphics modes are not supported. Fonts can be loaded (by using ROM BIOS INT 10h with AH = 11h) only into Character Generator Block 0.

Attribute Controller Registers

Before your application program uses the Attribute Controller registers (I/ O address 3C0h) in an extended interrupt 10h call, it must set the flip-flop that selects the address or data register so that it selects the address register (by doing an input from I/O port 3BAh or 3DAh). The flip- flop is always reset to this state upon return from the extended INT 10h call. Interrupt routines that access the attribute chip must also leave the flip-flop set to the address register upon return from the interrupt.

Note: If the application program sets the flip-flop so that it selects the Data register, and expects the flip-flop to remain in this state, the application must disable interrupts between the time it sets the flip-flop to the Data register state and the last time the flip-flop is assumed to be in this state.

Sequencer Memory Mode Register

When the Sequencer Memory Mode register (I/O address 3C5H, data register 4) is accessed, the sequencer produces a faulton the CAS lines that can cause problems with video random access memory. As a result, the application cannot use the EGA Register Interface to read from, or write to, this register. Instead, use the following procedure to safely alter this register:

  1. Disable interrupts
  2. Set Synchronous Reset (bit 1) in the Sequencer Reset register to 0
  3. 3.Read/modify/write the Sequencer Memory Mode register
  4. 4.Set Synchronous Reset (bit 1) in the Sequencer Reset register to 1
  5. 5.Enable interrupts

Input Status Registers

The application cannot use the EGA Register Interface to read Input Status registers 0 (I/O address 3C2h) and 1 (I/O address 3BAh or 3DAh). If the program must read these registers, it must do so directly.

Graphics Controller Miscellaneous Register

When the Graphics Controller Miscellaneous register (I/O address 3CFh, data register 6) is accessed, a glitch on the CAS lines occurs that can cause problems with video random access memory. As a result, the application should not use the EGA Register Interface to read from or write to this register.

EGA Register Interface Function F6h does not alter the state of the Graphics Controller Miscellaneous register. Instead, use the following procedure to safely alter this register:

  1. Disable interrupts
  2. Set Synchronous Reset (bit 1) in the Sequencer Reset register to 0
  3. Read/modify/write the Graphics Controller Miscellaneous register
  4. Set Synchronous Reset (bit 1) in the Sequencer Reset register to 1
  5. Enable interrupts

EGA Register Interface Functions

This section describes each EGA Register Interface function in detail. The following list shows these functions by function number (hex):

F0 Read One Register
F1 Write One Register
F2 Read Register Range
F3 Write Register Range
F4 Read Register Set
F5 Write Register Set
F6 Revert to Default Registers
F7 Define Default Register Table
F8 Read Default Register Table
FA Interrogate Driver

Note: Function F9h, and Functions FBh through FFh are reserved.

Each function description includes:

The parameters required to make the call (input) and the expected return values (output)
Any special considerations regarding the function

If the function description does not specify an input for a parameter, it is not necessary to supply a value for that parameter before making the call. If the function description does not specify an output value for a parameter, the parameter's value is the same before and after the call.

Note: The EGA Register Interface does not check input values, so be sure that the values loaded into the registers before making a call are correct.

Function F0H - Read One Register

This function reads data from a specified register on the EGA.

Input

AH = F0h

BX = Pointer for:

Pointer/data chips
BL = Pointer
Single registers
BX ignored.

DX = Port number:

Pointer/data chips
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
18h: Attribute Controller (3C0H)
Single registers
20h: Miscellaneous Output register (3C2H)
28h: Feature Control register (3?AH)
30h: Graphics 1 Position register (3CCH)
38h: Graphics 2 Position register (3CAH)

? = B for monochrome modes, or D for color modes

Output

AX: Restored

BH: Restored

BL: Data

DX: Restored

All other registers are restored.

Example

The following example saves the contents of the Sequencer Map Mask register in myvalue:

myvalue db   ?
        mov  ah, 0f0h        ; f0 = read one register
        mov  bx, 0002h       ; bh = 0 / bl = map mask index
        mov  dx, 0008h       ; dx = sequencer
        int  10h             ; get it!
        mov  myvalue, bl     ; save it!

The example below saves the contents of the Miscellaneous Output register in myvalue:

myvalue db   ?
        mov  ah, 0f0h        ; f0 = read one register
        mov  dx, 0020h       ; dx = miscellaneous output register
        int  10h             ; get it!
        mov  myvalue, bl     ; save it!

Function F1H - Write One Register

This function writes data to a specified register on the EGA. When an application program returns from a call to Function F1, the contents of registers BH and DX are not restored. The program must save and restore these registers.

Input

AH = F1h

BL = Pointer for pointer/data chips. Data for single registers.

BH = Data for pointer/data chips. Ignored for single registers.

DX = Port number:

Pointer/data chips
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
18h: Attribute Controller (3C0H)
Single registers

|{| |20h:||Miscellaneous Output register (3C2H) |- |28h:||Feature Control register (3?AH) |- |30h: Graphics 1 Position register (3CCH) |- |38h:||Graphics 2 Position register (3CAH) |} ? = B for monochrome modes or D for color modes

Output

AX: Restored

BL: Restored

BH: Not restored

DX: Not restored

All other registers are restored.

Example

The following example writes the contents of myvalue into the CRT Controller Cursor Start register:

myvalue db   3h
        mov  ah, 0f1h        ; f1 = write one register
        mov  bh, myvalue     ; bh = data from myvalue
        mov  bl, 000ah       ; bl = cursor start index
        mov  dx, 0000h       ; dx = crt controller
        int  10h             ; write it!

The example below writes the contents of myvalue into the Feature Control register:

myvalue db   2h
        mov  ah, 0f1h        ; f1 = write one register
        mov  bl, myvalue     ; bl = data from myvalue
        mov  dx, 0028h       ; dx = feature control register
        int  10h             ; write it!

Function F2H - Read Register Range

This function reads data from a specified range of registers on the EGA. A range of registers is defined to be several registers that have consecutive indexes, on a single chip. This function is applicable for pointer/data chips.

Input

AH = F2h

CH = Starting pointer value

CL = Number of registers (must be >1)

DX = Port number:

Pointer/data chips
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
18h: Attribute Controller (3C0H)

? = B for monochrome modes, or D for color modes

ES:BX = Points to table of one-byte entries (length = value in CL). On return, each entry is set to the contents of the corresponding register.

Output

AX: Restored

BX: Restored

CX: Not restored

DX: Restored

ES: Restored

All other registers are restored.

Example

The following example saves the contents of the Attribute Controller Palette registers in paltable:

paltable db  16 dup (?)
         mov  ax, ds               ; assume paltable in data segment
         mov  es, ax               ; es = data segment
         mov  bx, offset paltable  ; es:bx = paltable address
         mov  ah, 0f2h             ; f2 = read register range
         mov  cx, 0010h            ; ch = start index of 0
                                   ; cl = 16 registers to read
         mov  dx, 0018h            ; dx = attribute controller
         int  10h                  ; read them!

Function F3H - Write Register Range

This function writes data to a specified range of registers on the EGA. A range of registers is defined to be several registers that have consecutive indexes, on a single chip. This function is applicable for the pointer/data chips.

Input

AH = F3h

CH = Starting pointer value

CL = Number of registers (must be >1)

DX = Port number:

Pointer/data chips
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
18h: Attribute Controller (3C0H)

? = B for monochrome modes, or D for color modes

ES:BX = Points to table of one-byte entries (length = value in CL). Each entry contains the value to be written to the corresponding register.

Output

AX: Restored

BX: Not restored

CX: Not restored

DX: Not restored

ES: Restored.

All other registers are restored.

Example

The following example writes the contents of cursloc into the CRT Controller Cursor Location High and Cursor Location Low registers.

cursloc db   01h, 00h            ; cursor at page offset 0100h
        mov  ax, ds              ; assume cursloc in data segment
        mov  es, ax              ; es = data segment
        mov  bx, offset cursloc  ; es:bx = cursloc address
        mov  ah, 0f3h            ; f3 = write register range
        mov  cx, 0e02h           ; ch = start index of 14
                                 ; cl = 2 registers to write
        mov  dx, 0000h           ; dx = crt controller
        int  10h                 ; write them!

Function F4H - Read Register Set

This function reads data from a set of registers on the EGA. A set of registers is defined to be several registers that might have consecutive indexes and that might not be on the same chip.

Input

AH = F4h

CX = Number of registers (must be >1)

ES:BX = Points to table of records with each entry in this format:

Bytes 1-2: Port number:

Pointer/data chips
18h:||Attribute Controller (3C0H)
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
Single registers
20h: Miscellaneous Output register (3C2H)
28h: Feature Control register (3?AH)
30h: Graphics 1 Position register (3CCH)
38h: Graphics 2 Position register (3CAH)

? = B for monochrome modes, or D for color modes

Byte 3: Pointer value (0 for single registers)

Byte 4: EGA Register Interface fills in data read from register specified in bytes 1-3.

Output

AX: Restored

BX: Restored

CX: Not restored

ES: Restored.

All other registers are restored.

Example

The following example saves the contents of the Miscellaneous Output register, Sequencer Memory Mode register, and CRT Controller Mode Control register in results:

outvals dw   0020h               ; miscellaneous output register
        db   0                   ; 0 for single registers
        db   ?                   ; returned value
        dw   0008h               ; sequencer
        db   04h                 ; memory mode register index
        db   ?                   ; returned value
        dw   0000h               ; crt controller
        db   17h                 ; mode control register index
        db   ?                   ; returned value

results db   3 dup (?)
        mov  ax, ds              ; assume outvals in data segment
        mov  es, ax              ; es = data segment
        mov  bx, offset outvals  ; es:bx = outvals address
        mov  ah, 0f4h            ; f4 = read register set
        mov  cx, 3               ; number of entries in outvals
        int  10h                 ; get values into outvals
        mov  si, 3               ; move the returned values from
        add  si, offset outvals  ;  outvals
        mov  di, offset results  ;  to results
        mov  cx, 3               ; 3 values to move

loop:   mov  al, [si]            ; move one value from
        mov  [di], al            ;  outvals to results
        add  si, 4               ; skip to next source byte
        inc  di                  ; point to next destination byte
        loop loop

Function F5H - Write Register Set

This function writes data to a set of registers on the EGA. A set of registers is defined to be several registers that might have consecutive indexes, and that might be on the same chip.

Input

AH = F5h

CX = Number of registers (must be >1)

ES:BX = Points to table of values with each entry in this format:

Bytes 1-2: Port number:

Pointer/data chips
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
18h: Attribute Controller (3C0H)
Single registers
20h: Miscellaneous Output register (3C2H)
28h: Feature Control register (3?AH)
30h: Graphics 1 Position register (3CCH)
38h: Graphics 2 Position register (3CAH)

? = B for monochrome modes, or D for color modes

Byte 3: Pointer value (0 for single registers)

Byte 4: Data to be written to register specified in bytes 1-3.

Output

AX: Restored

BX: Restored

CX: Not restored

ES: Restored.

All other registers are restored.

Example

The following example writes the contents of outvals to the Miscellaneous Output register, Sequencer Memory Mode register, and CRT Controller Mode Control register:

outvals dw   0020h               ; miscellaneous output register
        db   0                   ; 0 for single registers
        db   0a7h                ; output value
        dw   0008h               ; sequencer
        db   04h                 ; memory mode register index
        db   03h                 ; output value
        dw   0000h               ; crt controller
        db   17h                 ; mode control register index
        db   0a3h                ; output value
        mov  ax, ds              ; assume outvals in data segment
        mov  es, ax              ; es = data segment
        mov  bx, offset outvals  ; es:bx = outvals address
        mov  ah, 0f5h            ; f5 = write register set
        mov  cx, 3               ; number of entries in outvals
        int  10h                 ; write the registers!

Function F6H - Revert to Default Registers

This function restores the default settings of any registers that the application program has changed through the EGA Register Interface. The default settings are defined in a call to Function F7 (described in the next section).

Input

AH = F6h

Output

All registers are restored.

Example

The following example restores the default settings of the EGA registers:

       mov  ah, 0f6h    ; f6 = revert to default registers
       int  10h         ; do it now!

Function F7H - Define Default Register Table

This function defines a table containing default values for any pointer/data chip or single register. If default values are defined for a pointer/data chip, they must be defined for all registers within that chip.

Input

AH = F7h

DX = Port number:

Pointer/data chips
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h: Graphics Controller (3CEH)
18h: Attribute Controller (3C0H)

|Single registers |{| |20h:||Miscellaneous Output register (3C2H) |- |28h: Feature Control register (3?AH) |- |30h:||Graphics 1 Position register (3CCH) |- |38h:||Graphics 2 Position register (3CAH) |} ? = B for monochrome modes, or D for color modes

ES:BX = Points to table of one-byte entries. Each entry contains the default value for the corresponding register. The table must contain entries for all registers.

Output

AX: Restored

BX: Not restored

DX: Not restored

ES: Restored

All other registers are restored.

Example

The following example defines default values for the Attribute Controller:

attrdflt db  00h, 01h, 02h, 03h, 04h, 05h, 06h, 07h
         db  10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h
         db  08h, 00h, 0fh, 00h
         mov  ax, ds              ; assume attrdflt in data segment
         mov  es, ax              ; es = data segment
         mov  bx, offset attrdflt ; es:bx = attrdflt address
         mov  ah, 0f7h            ; f7 = define default register table
         mov  dx, 0018h           ; dx = attribute controller
         int  10h                 ; do it!

The example below defines a default value for the Feature Control register:

featdflt db  00h
         mov  ax, ds              ; assume featdflt in data segment
         mov  es, ax              ; es = data segment
         mov  bx, offset featdflt ; es:bx = featdflt address
         mov  ah, 0f7h            ; f7 = define default register table
         mov  dx, 0028h           ; dx = feature control register
         int  10h                 ; do it!

Function F8H - Read Default Register Table

This function reads the table containing default register values for any pointer/data chip or single register.

Input

AH = 0F8H

DX = Port number:

Pointer/data chips
0h: CRT Controller (3?4H)
8h: Sequencer (3C4H)
10h Graphics Controller (3CEH)
18h Attribute Controller (3C0H)
Single registers
20h: Miscellaneous Output register (3C2H)
28h: Feature Control register (3?AH)
30h: Graphics 1 Position register (3CCH)
38h: Graphics 2 Position register (3CAH)

? = B for monochrome modes, or D for color modes

ES:BX = Points to a table into which the default values are returned. The table must have room for the full set of values for the pointer/data chip or single register specified.

Output

AX: Restored

BX: Not restored

DX: Not restored

ES: Restored

All other registers are restored.

Example

The following example reads the default values for the Miscellaneous Output register:

regdflt  db
         mov  ax, ds
         mov  es, ax               ; es = data segment
         mov  bx, offset regdflt   ; es:bx = regdflt address
         mov  ah, 0f8h             ; f8 = read default register table
         mov  dx, 0020h            ; dx = miscellaneous output register
         int  10h                  ; do it!

The following example reads the default values for the CRT Controller register:

regdflt  db   25 dup (?)
         mov  ax, ds
         mov  es, ax               ; es = data segment
         mov  bx, offset regdflt   ; es:bx = regdflt address
         mov  ah, 0f8h             ; f8 = read default register table
         mov  dx, 0000h            ; dx = crt controller register
         int  10h                  ; do it!

Function FAH - Interrogate Driver

This function returns a value specifying whether the EGA.SYS device driver is present.

Input

AH = FAh

BX = 0

Output

AX: Restored

BX: 0, if EGA.SYS driver is not present

ES:BX: Pointer to EGA Register Interface version number, if present

Byte 1: Major release number

Byte 2: Minor release number (in 1/100ths)

Example

The following example interrogates the driver and displays the results:

gotmsg  db   "EGA.SYS driver found", 0dh, 0ah, 24h
nopmsg  db   "EGA.SYS driver not found", 0dh, 0ah, 24h
revmsg  db   "revision $"
crlf    db   0dh, 0ah, 24h
ten     db   10
        mov  bx, 0              ; must be 0 for this call
        mov  ah, 0fah           ; fa = interrogate driver
        int  10h                ; interrogate!
        or   bx, bx             ; bx = 0 ?
        jnz  found              ; branch if driver present
        mov  dx, offset nopmsg  ; assume nopmsg in data segment
        mov  ah, 09h            ; 9 = print string
        int  21h                ; output not found message
        jmp  continue           ; that's all for now
found:  mov  dx, offset gotmsg  ; assume gotmsg in data segment
        mov  ah, 09h            ; 9 = print string
        int  21h                ; output found message
        mov  dx, offset revmsg  ; assume revmsg in data segment
        mov  ah, 09h            ; 9 = print string
        int  21h                ; output "revision "
        mov  dl, es:[bx]        ; dl = major release number
        add  dl, "0"            ; convert to ASCII
        mov  ah, 2              ; 2 = display character
        int  21h                ; output major release number
        mov  dl, "."            ; dl = "."
        mov  ah, 2              ; 2 = display character
        int  21h                ; output a period
        mov  al, es:[bx+1]      ; al = minor release number

        xor  ah, ah             ; ah = 0
        idiv ten                ; al = 10ths, ah = 100ths
        mov  bx, ax             ; save ax in bx
        mov  dl, al             ; dl = 10ths
        add  dl, "0"            ; convert to ASCII
        mov  ah, 2              ; 2 = display character
        int  21h                ; output minor release 10ths
        mov  dl, bh             ; dl = 100ths
        add  dl, "0"            ; convert to ASCII
        mov  ah, 2              ; 2 = display character
        int  21h                ; output minor release 100ths
        mov  dx, offset crlf    ; assume crlf in data segment
        mov  ah, 09h            ; 9 = print string
        int  21h                ; output end of line
continue:                       ; the end

INT 2Fh Screen Switch Notification

A new Multiplex Interrupt (INT 2Fh) is issued by OS/2 to signal either of the following two events:

Switching the DOS application to the background (AX = 4001H)
Switching the DOS application to the foreground (AX = 4002H)

A DOS application that receives this signal must hook the Multiplex Interrupt vector. That is, when the application is started, it must save the current INT 2Fh vector and set this vector to point to the application's interrupt handler.

When the notification is received, the application must save all registers, perform whatever processing is required, restore all registers, and issue the IRET instruction to return to the operating system. Only the following forms of processing are supported:

Modifying application or video memory (or both)
Issuing ROM BIOS video service calls (INT 10h)
Issuing EGA Register Interface calls (INT 10h)
Programming the EGA video card directly

Note: When an application is being switched to the background, and the application's INT 2Fh handler uses the EGA Register Interface to save the EGA registers, these registers are restored automatically when the application is returned to the foreground.

An application can receive notification that it is being switched to the background at any time. Code sequences that are sensitive to interruption can be protected with CLI/STI instructions. When the switch notification occurs, the application (other than its INT 2Fh handler) is frozen until it is returned to the foreground.

When an application's INT 2Fh handler receives notification with a value in AH other than 40H, the application must issue the JMP FAR instruction to branch to the previous INT 2Fh vector.

Using Extended Screen and Keyboard Control (ANSI.SYS, ANSICALL)

This section explains how to issue special control character sequences to:

Control the position of the cursor
Erase text from the screen
Set the display mode
Redefine the meaning of keyboard keys

ANSI extended screen and keyboard control sequences are supported in DOS sessions by ANSI.SYS, an installable device driver. In OS/2 sessions, these control sequences are supported by the ANSICALL component within OS/2 CHAR. DLL.

Note: In this section, unless otherwise specified, ANSI refers to both ANSI.SYS and ANSICALL.

Limitations and Restrictions

ANSI operates on a per-session basis. OS/2-mode ANSI is affected when keys are reassigned in a code page environment. ANSI does not provide code page support for key reassignment in a DOS session.

Control Sequence Syntax

Each of the cursor control sequences is in the format:

ESC [ parameters COMMAND

A cursor control sequence is defined as follows:

Sequence Description
ESC The 1-byte ASCII code for ESC (1BH). It is not the three characters ESC.
[ The character [.
parameters The numeric values specified for #. The # represents a numeric parameter that is an integer value specified with ASCII characters. If a parameter value is not specified, or if a value of 0 (zero) is specified, the default value for the parameter is used.
COMMAND An alphabetic string that represents the command. It is case-specific.

For example, ESC [2;10H could be created using BASIC as shown below. Notice that "CHR$(27)" is ESC.

The IBM Personal Computer Basic Version 3.00 Copyright IBM Corp. 1981, 1982, 1983, 1984
xxxxx Bytes free

OK
open "sample" for output as 1
OK
print #1, CHR$(27);"[2;10H";"x row 2 col 10"
OK
close #1
OK

Cursor Control Sequences

The following tables contain the cursor control sequences used to control cursor positioning:

Cursor Position Function
ESC [#;#H Moves the cursor to the position specified by the parameters. The first parameter specifies the row number and the second parameter specifies the column number. The default value is 1. If no parameter is given, the cursor is moved to the home position.

This example copies the file SAMPLE from the previous example to CON, that places the cursor on row 2, column 10 of the screen:

type sample
Cursor Up Function
ESC [#A Moves the cursor up one or more rows without changing the column position. The value of # determines the number of lines moved. The default value for # is 1. This sequence is ignored if the cursor is already on the top line.
Cursor Down
ESC [#B Moves the cursor down one or more rows without changing the column position. The value of # determines the number of lines moved. The default value for # is 1. The sequence is ignored if the cursor is already on the bottom line.
Cursor Forward
ESC [#C Moves the cursor forward one or more columns without changing the row position. The value of # determines the number of columns moved. The default value for # is 1. This sequence is ignored if the cursor is already in the rightmost column.
Cursor Backward
ESC [#D Moves the cursor back one or more columns without changing the row position. The value of # determines the number of columns moved. The default value for # is 1. This sequence is ignored if the cursor is already in the leftmost column.
Horizontal and Vertical Position
ESC [#;#f Moves the cursor to the position specified by the parameters. The first parameter specifies the line number and the second parameter specifies the column number. The default value is 1. If no parameter is given, the cursor is moved to the home position.
Cursor Position Report
ESC [#;#R The cursor sequence report reports the current cursor position through the standard input device. The first parameter specifies the current line and the second parameter specifies the current column.
Device Status Report
ESC [6n The console driver gives a cursor position report sequence on receipt of device status report.

Note: Do not use the Device Status Report as part of a prompt.

This example tells ANSI to put the current cursor position (row and column) in STDIN. Then the program reads it from STDIN and outputs it to STDOUT.

PROGRAM dsr(INPUT,OUTPUT);

  VAR
    f:FILE OF CHAR;
    key:CHAR;

  FUNCTION inkey:CHAR;                    { read character  }
    VAR                                   { from the  /Using a File
      ch:CHAR;                            { keyboard buffer }
    BEGIN
      READ(f,ch);
      inkey:=ch
    END;

  BEGIN
    ASSIGN(f,'user');
    RESET(f);
        WRITE(CHR(27),'[6n');             { issue a DSR,  }
        key:=inkey;                       { read up to    }
        key:=inkey;                       { first digit   }
        key:=inkey;                       { of the row    }
        WRITE('row ',inkey,inkey,'  column ');
        key:=inkey;                       { skip to column}
        WRITE(inkey,inkey)                { write column  }
  END.
Save Cursor Position Function
ESC [s The current cursor position is saved. This cursor position can be restored with the restore cursor position sequence (see below).
Restore Cursor Position
ESC [u Restores the cursor to the value it had when the console driver received the save cursor position sequence.

Erasing

The following tables contain the control sequences used to erase text from the screen:

Erase in Display Function
ESC [2J Erases all of the screen, and the cursor goes to the home position.
Erase in Line
ESC [K Erases from the cursor to the end of the line and includes the cursor position.

Controlling the Display Mode

The following tables contain the control sequences used to set the mode of operation:

Set Graphics Rendition (SGR)
Set Mode (SM)

Reset Mode (RM)

Set Graphics Rendition (SGR) Function
ESC [#;...;#m Sets the character attribute specified by the parameters. All of the following characters have the attribute according to the parameters until the next occurrence of SGR. 31||Red foreground
Parameter Meaning
0 All attributes off (normal white on black
1 Bold on (high intensity)
4 Underscore on (monochrome compatible modes)
5 Blink on
7 Reverse video on
8 Canceled on (invisible)
30 Black foreground
32 Green foreground
33 Yellow foreground
34 Blue foreground
35 Magenta foreground
36 Cyan foreground
37 White foreground
38 Reserved
39 Reserved
40 Black background
41 Red background
42 Green background
43 Yellow background
44 Blue background
45 Magenta background
46 Cyan background
47 White background
Set Mode (SM) Function
ESC [=#h
or ESC [=h
or ESC [=0h
or ESC [?7h
Invokes the screen width or type specifiedby the parameter.
Parameter Meaning
0 40 x 25 black and white
1 40 x 25 color
2 80 x 25 black and white
3 80 x 25 color
4 320 x 200 color
5 320 x 200 black and white
6 640 x 200 black and white
7 Wrap at end of line. Typing past end-of-line results in new line.
Reset Mode (RM) Function
ESC [=#l
or ESC [=l
or ESC [=0l
or ESC [?7l
Parameters are the same as Set Mode (SM) except that parameter 7 resets wrap at end-of-line mode (characters past end-of-line are discarded).

Keyboard Key Reassignment

The ANSI system can be used to reassign keys on the keyboard. When an application calls KbdStringIn, the reassigned key's ASCII code is converted to the specified string and is passed back to the calling application. For example, replace a with q so that whenever the a key is pressed, a q is passed to the application that is reading input.

In OS/2 2.1, keyboard remapping can be done only from an application calling KbdStringIn. In DOS, keyboard remapping must be done from the command line.

Note: Keyboard reassignment works only with OS/2 applications that use the KbdStringIn call to get input.

OS/2 mode ANSI is affected when keys are reassigned in a code-page environment. ANSI "remembers" the code page under which a key is reassigned . The keyboard subsystem checks for reassigned keys when the application calls the KbdStringIn function. When a reassigned key is detected, the ANSI support:

  1. Checks to see what code page the requestor is running under
  2. Looks internally to see if the key has been reassigned under that code page
  3. If there is a key reassignment for that code page, gives the reassignment string
  4. Otherwise, gives the original ASCII codes.

A maximum storage of 64KB can be allocated to OS/2 mode ANSI-reassigned key definitions. The table shown below contains the control sequences used to redefine the meaning of keyboard keys:

The control sequence is: Function
ESC [#;#;...#p
or ESC ["string"p
or ESC [#;"string";#;#; "string";#p
or any other combination of strings and decimal numbers
The first ASCII code in the control sequence defines which code is being mapped. The remaining numbers define the sequence of ASCII codes generated when this key is intercepted. However, if the first code in the sequence is 0 (NULL), the first and second code make up an extended ASCII redefinition.

To execute the examples below, either create a file that contains the following statements and then use the TYPE command to display the file that contains the statement, or execute the command at the OS/2 prompt:

Assign the Aand akey to the Qand qkey, respectively.
Assign the Qand qkey to the Aand akey, respectively:

Using a File:

ESC [65;8lp          A becomes Q
ESC [97;113p         a becomes q
ESC [81;65p          Q becomes A
ESC [113;97p         q becomes a

At the OS/2 Prompt:

prompt $e[65;8lp     A becomes Q
prompt $e[97;113p    a becomes q
prompt $e[81;65p     Q becomes A
prompt $e[113;97p    q becomes a
Reassign the F10 key to a DIR command followed by a carriage return:

Using a File:

ESC [0;68;"dir";13p

At the OS/2 Prompt:

 prompt $e[0;68;"dir";13p

The $e is the prompt command characters for ESC. The 0;68 is the extended ASCII code for the F10 key; 13 decimal is a carriage return.

The following example sets the prompt to display the current directory on the top of the screen and the current drive on the current line:
   prompt $e[s$e[1;30f$e[K$p$e[u$n$g

If the current directory is C:\FILES, and the current drive is C, this example would display:

            C:\FILES
C>
The following DOS-compatible assembly language program reassigns the F10 key to a DIR B: command followed by a carriage return:
        TITLE SET ANSI.ASM - SET F10 TO STRING FOR ANSI.SYS

CSEG    SEGMENT PARA PUBLIC 'CODE'
        ASSUME  CS:CSEG,DS:CSEG
        ORG     100H
ENTPT:  JMP     SHORT START
STRING  DB      27,'[0;68;"DIR B:";13P' ;Redefine F10 key
STRSIZ  EQU     $-STRING                ;Length of above message
HANDLE  EQU     1                       ;Pre-defined file.
                                        ;Handle for standard output

START   PROC    NEAR
        MOV     BX,HANDLE               ;Standard output device
        MOV     CX,STRSIZ               ;Get size of text to be sent
        MOV     DX,OFFSET STRING        ;Pass offset of string
                                        ;To be sent
        MOV     AH,40H                  ;Function="write to device"
        INT     21h                     ;Call DOS
        RET                             ;Return to DOS
START   ENDP

CSEG    ENDS
        END     ENTPT

DPRINTF Print Formatting Package

DPRINTF is a kernel-debugging print-formatting package. You can include this function in the code to test your display driver.

To use the DPRINTF function, you must have a second device attached to COM1 or COM2. Due to difficulties passing variable-length argument lists through a call-gate transition, only one argument, a 0-terminated string, is passed to this routine. The string is sent to either COM1 or COM2 depending on how the variable, UR_DAT, is defined.

The only checking that this routine performs is to process XON/XOFF characters from the equipment attached to the debug port. This guarantees that the output does not overrun the receiving device. However, after receiving XOFF, this routine spins in a loop, waiting for XON.

The string to be output is ASCIIZ. It may contain literal characters.

A literal character is defined as any character that is not part of a format specification. Special non-printing characters are listed as follows :

\n for CRLF (carriage return/linefeed)
\t for tab
\b for bell
\\ for \.