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BIOS Disk Definition Tables
7-2
Table 7-1 Disk Parameter Header Elements
ELEMENT
DESCRIPTION
XLT
Offset of the logical-to-physical translation vector, ifused for this
particular drive, or the value OOOOH if no sector translation takes
place (i.e., the physical and logical sector numbers are the same).
Disk drives with identical sector skew factors share the same
translate tables.
0000
Scratchpad values for use within the BDOS (initial value is
unimportant).
DIRBUF
Offset of a 128-byte scratchpad area for directory operations
within BDOS. All DPHs address the same scratchpad area.
DPB
Offset of a disk parameter block for this drive. Drives with
identical disk characteristics address the same disk parameter
block.
CSV
Offset of a scratchpad area used for software check for changed
disketts. This offset is different for each DPH and is used for
floppy diskettes only.
ALV
Offset of a scratchpad area used by the BDOS to keep disk storage
allocation information. This offset is different for each DPH.
Table 7-2 lists the DPH values for the APC.
DIRBUF
CSV
ALV
Table 7-2 DPH Values For The APe
FO-ID
FD-2D
128 bytes
128 bytes
16 bytes
64 bytes
x 4 drives
x 4 drives
31 bytes
62 bytes
x 4 drives
x 4 drives
HARD DISK
128 bytes
a
71 bytes
x 4 drives
CPMSPT= 64
SECMSK
=
63
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