Digital Equipment DECmpp12000, Reference Manual

Page: 118 / 156

A.3 System Configuration Table
Table A–12 (Cont.) Values for Disk Parameter Table
Sub-
DrvID Byte
Offset
RW Type Name Value
3 34h RW Number of data heads 00h . . . FFh
3 35h RW Number of sectors/track 00h . . . FFh
3 36h RW Number of skip sectors 00h . . . FFh
3 37h RW Number of reserved
cylinders
00h . . . FFh
3 38h RW Unformatted bytes/track 00h . . . FFh (byte 1)
3 39h RW Unformatted bytes/track 00h . . . FFh (byte 0)
3 3Ah RW Unformatted bytes/sector 00h . . . FFh (byte 1)
3 3Bh RW Unformatted bytes/sector 00h . . . FFh (byte 0)
3 3Ch RW Number of bytes/PLO sync 00h . . . FFh
3 3Dh RW Reserved
4 40h RO Reserved
..
.
..
.
..
.
..
.
..
.
F FFh RO Reserved
The upper 4 bits of the Byte Offset reference the Sub Drive ID code.
A.3.4 Bad Block Table
Entries in the Bad Block Table (BBT) are in ascending sorted order. The 256
bytes of a BBT page are organized as shown in Table A–13.
Table A–13 Bad Block Table Byte Organization
Byte Offset RW Type Name Value
00h RO Cylinder 00h . . . 0Fh (byte 1)
01h RO Cylinder 00h . . . FFh (byte 0)
02h RO Head 00h . . . FFh
03h RO Sector 00h . . . FFh
04h RO Block 00h . . . FFh (byte 3)
05h RO Block 00h . . . FFh (byte 2)
06h RO Block 00h . . . FFh (byte 1)
07h RO Block 00h . . . FFh (byte 0)
08h RO Cylinder 00h . . . 0Fh (byte 1)
09h RO Cylinder 00h . . . FFh (byte 0)
0Ah RO Head 00h . . . FFh
0Bh RO Sector 00h . . . FFh
0Ch RO Block 00h . . . FFh (byte 3)
0Dh RO Block 00h . . . FFh (byte 2)
0Eh RO Block 00h . . . FFh (byte 1)
(continued on next page)
A–18 Configuration Data