MEM 0040h:0042h - DISK - FLOPPY/HARD DRIVE STATUS/COMMAND BYTES
Size: 7 BYTEs
SeeAlso: MEM 0040h:0041h
42h BYTE XTIBM PC XT: command byte to hard disk controller
ATIBM PC AT: write precompensation cylinder number / 4
43h BYTE XTIBM PC XT: bit 5 = drive number, bits 3-0=head number
ATIBM PC AT: sector count
44h BYTE XTIBM PC XT: bits 6,7 = high bits of track, bits 5-0 = start sector-1
ATIBM PC AT: starting sector
45h BYTE low byte of track number
46h BYTE XTIBM PC XT: sector count
ATIBM PC AT: high bits of track number
47h BYTE XTIBM PC XT: controlbyte from HD parameters (step rate,...)
ATIBM PC AT: 101DHHHH, D=drive number, HHHH=head number
bit 7 = ECC mode (1)
bit 6 = unknown (0)
bit 5 = 512 byte sectors (1)
bit 4 = drive number
bit 3-0 head number
48h BYTE XTIBM PC XT: INT 13h subfunction number
ATIBM PC AT: command byte to hard disk controller
SeeAlso: CALL F000h:211Eh