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Writes the string to the display, with the current cursor position as the starting point. When the write is finished, the cursor is moved to one position past the end of the string.


VioWrtTTY (CharStr, Length, VioHandle);


CharStr (PCH) - input 
Character string to be written. The address of the string to be written.
Length (ULONG) - input 
Length of the character string in bytes.
VioHandle (HVIO) - input 
VIO presentation-space handle.
This value is to be zero, unless the caller is a Presentation Manager application. If this is the case, the value need to be from VioCreatePS.




APIRET with values of:

  • 0 NO_ERROR

Define (C/C++)


Calling Convention


Example Code

PCH     string;
ULONG  strLength;
HVIO   videoHndl;
rc = VioWrtTTY(string, strLength, videoHndl);


If a string write gets to the end of the line and is not complete, the string write continues at the beginning of the next line. If the write gets to the end of the screen, the screen is scrolled, and the write continues until completed.

The character's carriage return, line feed, backspace, tab, and bell are treated as commands rather than printable characters. Backspace is a nondestructive backspace. Tabs are expanded to provide standard 8-byte-wide fields. VioWrtTTY is the only video function affected by ANSI.

Characters are written using the current attribute defined by ANSI or the default value of 7.


The behaviour of VioWrtTTY is: If the string is at line's end it is continued on the next line. If the string is at the screen's end; the screen is scrolled until write is completed.

These items are treated as commands and not printable characters:

  • carriage return
  • line feed
  • backspace
  • tab
  • bell

Backspaces are not destructive. Tabs are expanded into 8-byte wide fields. VioWrtTTY is the only video function affected by ANSI.

Here is some documentation, based on my hello world.

The following is a prototype, that works with OpenWatcom 1.3.

APIRET VioWrtTTY( char *string, unsigned short length, unsigned short VioHandle );

To get the prototype do:

#define INCL_VIO
#include <os2.h>

The Control Program Programming Guide and Reference (that comes with the OS/2 Tool Kit 4.52) documents string as PCH, which is unsigned char * but that does not work with OpenWatcom 1.3.

The VioHandle must be 0, unless the caller is a Presentation Manager application, and then it must have been returned by VioCreatePS.

A sample, hello world:

#define INCL_VIO
#include <os2.h>

int main( int argc, char *argv[] )
        APIRET rc = VioWrtTTY( "Hello, VIO\n", // string to write
                               11,             // lenght of string to write
                               0 );            // VIO handle, must be 0
        return rc;