DSK_SETDEVICEPARAMS
- Category
- IOCTL_DISK (08h)
- Function
- DSK_SETDEVICEPARAMS (43h)
- Description
- Set Device Parameters
Description
This function sets the parameters for a specified device.
Parameter Packet Format
| Field | Length | C Datatype |
|---|---|---|
| Command Information | BYTE | UCHAR |
| Drive Unit | BYTE | UCHAR |
Data Packet Format
| Field | Length | C Datatype |
|---|---|---|
| Extended BPB for Devices | 31 BYTES | BYTE[31] |
| Number of Cylinders | WORD | USHORT |
| Device Type | BYTE | BYTE |
| Device Attributes | WORD | USHORT |
Returns
Possible values are shown in the following list:
| Code | Description |
|---|---|
| 0 | NO_ERROR |
| 1 | ERROR_INVALID_FUNCTION |
| 6 | ERROR_INVALID_HANDLE |
| 15 | ERROR_INVALID_DRIVE |
| 31 | ERROR_GEN_FAILURE |
| 87 | ERROR_INVALID_PARAMETER |
| 111 | ERROR_BUFFER_OVERFLOW |
| 111 | ERROR_BUFFER_OVERFLOW |
| 115 | ERROR_PROTECTION_VIOLATION |
| 117 | ERROR_INVALID_CATEGORY |
| 119 | ERROR_BAD_DRIVER_LEVEL |
| 163 | ERROR_UNCERTAIN_MEDIA |
| 165 | ERROR_MONITORS_NOT_SUPPORTED |
Remarks
The Command Information field uses the two low bits to indicate one of three actions: 00 (revert to building the BIOS Parameter Block (BPB) off the medium for all subsequent Build BPB functions, typically used after a format to reset device parameters), 01 (change the default BPB for the physical device, altering the drive's physical parameters), or 10 (change the BPB for the medium to the specified BPB and return the new BPB for subsequent Build BPB calls, used to prepare for a format operation). All other bits are reserved and must be set to 0. The Drive Unit field (0=A, 1=B, 2=C, etc.) is used only when the IOCtl is issued without a previously allocated file handle (using a file handle of -1) and when Command Information is set to 01; media in the drive is not required.
The Extended BPB describes the media structure and physical drive layout (heads, tracks, sectors) with fields: Bytes per Sector (WORD), Sectors per Cluster (BYTE), Reserved Sectors (WORD), Number of FATs (BYTE), Root Directory Entries (WORD), Total Sectors (WORD), Media Descriptor (BYTE), Sectors per FAT (WORD), Sectors per Track (WORD), Number of Heads (WORD), Hidden Sectors (DWORD), Large Total Sectors (DWORD), and Reserved (6 BYTES). The Number of Cylinders indicates the cylinders defined for the physical device. Device Type specifies the physical layout: 0 (48 TPI low-density diskette), 1 (96 TPI high-density diskette), 2 (3.5-inch 720KB), 3 (8-inch single-density diskette), 4 (8-inch double-density diskette), 5 (fixed disk), 6 (tape drive), 7 (other, including 1.44MB 3.5-inch diskette), 8 (R/W optical disk), or 9 (3.5-inch 4.0MB diskette). Device Attributes is a bit field: Bit 0 (1 for non-removable media, 0 for removable), Bit 1 (1 if the device supports detecting media removal since the last I/O, 0 otherwise, requiring a Media Check via Strategy Command 1h).
The BIOSPARAMETERBLOCK data structure can be used by C programmers by defining INCL_DOSDEVIOCTL before including OS2.H.