DIGITAL-LOGIC Microspace MSM586SEN - Page 68

DIGITAL-LOGIC AG MSM586SEN/SEV Manual V1.5E
68
BIOS Data Area Definitions Continued...
Location Description
78h - 7Bh Default parallel port timeout values
7Dh - 7Fh Default serial port timeout values
80h - 81h Pointer to start of keyboard buffer
82h - 83h Pointer to end of keyboard buffer
84h - 88h Reserved for EGA/VGA BIOS
8Ah Reserved
8Bh
Diskette drive data transfer rate information
bits 7-5 = Data rate on last operation
00 = 500 KBS
01 = 300 KBS
10 = 250 KBS
bits 5-4 = Last drive step rate selected
bits 3-2 = Data transfer rate at start of operation
00 = 500 KBS
01 = 300 KBS
10 = 250 KBS
bits 1-0 = Reserved
8Ch
Copy of hard status register
8Dh Copy of hard drive error register
8Eh Hard drive interrupt flag
8Fh Diskette controller information
bit 7 = Reserved
bit 6 = (1) Drive confirmed for drive B
bit 5 = (1) Drive B is multi-rate
bit 4 = (1) Drive B supports line change
bit 3 = Reserved
bit 2 = (1) Drive determined for drive A
bit 1 = (1) Drive B is multi-rate
bit 0 = (1) Drive B supports line change
90h - 91h Media type for drives
bits 7-6 = Data transfer rate
00 = 500 KBS
01 = 300 KBS
10 = 250 KBS
bit 5 = (1) Double stepping required when 360K
diskette inserted into 1.2MB drive
bit 4 = (1) Known media is in drive
bit 3 = Reserved
bits 2-0 = Definitions upon return to user applications
000 = Testing 360K in 360K drive
001 = Testing 360K in 1.2 MB drive
010 = Testing 1.2 MB in 1.2 MB drive
011 = Confirmed 360K in 360K drive
100 = Confirmed 360K in 1.2 MB
101 = Confirmed 1.2 MB in 1.2 MB drive
111 = 720K in 720K drive or 1.44 MB in
1.44 MB drive
Continued...