Category: DOS kernel
INT 21 - DOS 3.2+ - IOCTL - GENERIC CHARACTER DEVICE REQUEST AX = 440Ch BX = device handle CH = category code (see #01545) CL = function number (see #01546) DS:DX -> parameter block (see #01547,#01548,#01549,#01550,#01551,#01552) SI = parameter to pass to driver (European MS-DOS 4.0, OS/2 comp box) DI = parameter to pass to driver (European MS-DOS 4.0, OS/2 comp box) Return: CF set on error AX = error code (see #01680 at AH=59h/BX=0000h) CF clear if successful DS:DX -> iteration count if CL=65h SI = returned value (European MS-DOS 4.0, OS/2 comp box) DI = returned value (European MS-DOS 4.0, OS/2 comp box) Note: DR DOS 3.41 and 5.0 return error code 16h on CL=45h,65h if the device does not support a retry counter SeeAlso: AX=440Dh"DOS 3.2+",INT 2F/AX=0802h,INT 2F/AX=122Bh,INT 2F/AX=14FFh SeeAlso: INT 2F/AX=1A01h