HP 7925D Service Manual page 187

7925
Appendix A
14 BYTES
SECTOR 1
CRC
®
ECC
@
2 BYTES 12 BYTES
DATA
CD
256 BYTES
CYLINDER
SECTOR 0
2 BYTES
SYNC WORD
30 BYTES
SECTOR 63
PREAMBLE
CD
8 7 6 5 8
CD
PREAMBLE - 30 BYTES FOR SYNCHRONIZATION AND ADDRESSING
<y
DATA - 256 BYTES OF DATA
G)
POSTAMBLE - DATA CHECKING AND ERROR CORRECTION INFORMATION
o
SYNC FIELD - 24 BYTES (192 BITS) OF'O'S
@
SYNC - SYNC WORD - 100376 8 IF ECC FIELD IS VALID
100377
8
OTHERWISE
@
CYLAD - CYLINDER - CYLINDER ADDRESS
G)
HSAD - S - IF "1", SPARE TRACK IN ACTIVE USE (BIT
8)
P - IF "1", PROTECTED TRACK (BIT 7)
D - IF "1", DEFECTIVE TRACK (BIT 6)
HEAD - HEAD ADDRESS (BITS 5 -1)
SECTOR - SECTOR ADDRESS (BITS
8-11
®
CRC - CYCLIC REDUNDANCY CHECK - 2 BYTES OF CHECK INFQRMATION
@
ECC - ERROR CORRECTION CODE - 12 BYTES OF CHECK AND CORRECTION INFORMATION.*
*NOT WRITTEN OR READ BY HP 7925H.
7311-92
Figure A-5. HP 7925H Sector Format
A·5