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Copyright 1991 David Jurgens |
INT 21,37 - Get/Set Switch Character (Undocumented, DOS 2.0+)
AH = 37h
AL = 0 get switch character into DL; some systems return "-"
= 1 set switch character to value in DL
= 2 read device prefix flag into DL; returns DL = 0 indicating
devices must be accessed using /DEV/device. A non-zero value
indicates devices may be accessed without prefix
= 3 set device prefix flag, device names must begin with \DEV\.
DL = new switch character (AL=1)
= 00 \DEV\ must preceed device names (AL=3)
= 01 \DEV\ is not neccesary in device names (AL=3)
on return:
AL = FF illegal subfunction code specified
DL = current switch character (AL=0)
= device availability (AL=2, always FF with DOS 4.x+)
- subfunctions 0 and 1 were formerly available as a CONFIG.SYS
command in DOS versions before 3.x; also supportedin the OS/2
compatibility box
- subfunctions 2 and 3 were available in DOS 2.x only; they have
no effect in DOS 4.x+
- /DEV/ prefix is valid in DOS 2.x by default, setting the flag makes
it mandatory. DOS internal commands like DIR, TYPE and DEL do not
recognize filenames the are identical to device names regardless of
the setting of the AVAILDEV flag.
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| Esc or Alt-X to exit |
int 21,37 |
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