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Copyright 1991 David Jurgens |
INT 21,44,C / IOCTL,C - Generic I/O for Handles
AH = 44h
AL = 0C
BX = handle
CH = device type
= 00 unknown device type (DOS 3.3+)
= 01 COMx (DOS 3.3+)
= 03 CON (DOS 3.3+)
= 05 LPTx (DOS 3.3+), printer (DOS 3.2)
CL = minor function code (when CH = 3 or CH = 5)
= 45 set iteration count (DOS 3.2 only)
= 4A select code page (DOS 3.3+); parameter format:
00 word length of data
02 word code page ID
04 nwords character set data array (see offset 00)
= 4C code page prepare start (DOS 3.3+); parameter format:
00 word flags
02 word length of remainder of parameter block
04 word number of code pages following
06 nwords code page 1,...,N
= 4D code page prepare end (DOS 3.3+); parameter format:
00 word length of data
02 word code page ID
= 5F set display info (DOS 4.x, when CH=3); parameter format:
00 byte level (0 for DOS 4.0)
01 byte reserved
02 word length of following data
04 word control flags
bit 0 set for blink, clear for intensity
bits 1 to 15 reserved
06 byte mode type (1=text, 2=graphics)
07 byte reserved
08 word colors; 0=monochrome, n=bits per pixel
0A word pixel columns
0C word pixel rows
0E word character columns
10 word character rows
= 65 get iteration count (DOS 3.2 only)
= 6A query selected code page (DOS 3.3+); parameter format:
00 word length of data
02 word code page ID
04 nwords character set data array (see offset 00)
= 6B query prepare list (DOS 3.3+); Parameter format:
00 word length of following data
02 word number of hardware code pages
04 nwords hardware code page array
xx word number of prepared code pages
xx nwords prepared code page array
= 7F get display info (DOS 4.x, CH = 3)
00 byte level (0 for DOS 4.0)
01 byte reserved
02 word length of following data
04 word control flags
bit 0 set for blink, clear for intensity
bits 1 to 15 reserved
06 byte mode type (1=text, 2=graphics)
07 byte reserved
08 word colors; 0=monochrome, n=bits per pixel
0A word pixel columns
0C word pixel rows
0E word character columns
10 word character rows
DS:DX = pointer to iteration count word (DOS 3.2)
= pointer to parameter block (DOS 3.3)
on return
AX = error code if CF set (see DOS ERROR CODES)
- iteration count word specifies the number of times to retry
an operation before aborting
- DOS 3.3 changed this function to handle code page switching
- implemented from DOS 3.2
- DOS 4.x adds support for double byte characters
- see IBM DOS Technical Reference Manual for more details
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| Esc or Alt-X to exit |
int 21,44,c |
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