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COMMAND CODE FIELD
The command code field in the request header can have the
following values:
CODE FUNCTION
0 INIT
1 MEDIA CHECK (block only,NOP for character)
2 BUILD BPB (block only, NOP for
character)
3 IOCTL input (called only if IOCTL bit is
1)
4 INPUT (read)
5 NONDESTRUCTIVE INPUT NO WAIT (character devices
only)
6 INPUT STATUS (character devices only)
7 INPUT FLUSH (character devices only)
8 OUTPUT (write)
9 OUTPUT (write with verify)
10 OUTPUT STATUS (character devices only)
11 OUTPUT FLUSH (character devices only)
12 IOCTL OUTPUT (called only if IOCTL bit is
1)
13 DEVICE OPEN (called only if OPEN/CLOSE/RM
bit is set)
14 DEVICE CLOSE (called only if OPEN/CLOSE/RM
bit is set)
15 REMOVEABLE MEDIA (called only if OPEN/CLOSE/RM
bit is set and device is
block)
NOTE: Command codes 13,14,and 15 are for use with DOS
versions 3.x |
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