## Virtual Device Driver Reference for OS/2

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### DOS Software Interrupt Support

The DOS emulation component supports the documented aspects of the following DOS features:

20h Program Terminate.

21h DOS Function Request. All documented and undocumented INT 21h functions are supported by DOS emulation. However the following functions are supported, with restrictions:

4410h
4411h
4B05h
5Dh
5Eh
5Fh
64h
69h
6Dh
6Eh

Note: Function 53h is not supported by DOS emulation.

22h Terminate Address.

23h Ctrl+Break Exit Address.

24h Critical Error Handler.

25h Absolute Disk Read.

26h Absolute Disk Write. A hard error is reported on requests for nonremovable media.

27h Terminate-and-Stay-Resident.

28h Idle Loop.

2Fh Multiplex. Time slice yield (AX = 1680h) is supported. When a DOS application issues INT 2Fh with AX = 1680h, it offers to yield its time slice. This can be used by DOS applications in busy wait loops (preserves all registers).