Specifications

AMD Geode™ GeodeROM Functional Specification 65
Non-Removable Media
32087C
76h
1
BYTE Head control byte (= 8 if head count > 8).
77h BYTE Reserved.
78h 3 BYTEs Timeout count bytes for LPT1-LPT3.
79h BYTE Reserved.
7Ch 4 BYTEs Timeout count bytes for COM1-COM3 devices.
80h WORD Keyboard buffer start location override (relative to 40:0h).
82h WORD Keyboard buffer end offset + 1 override (relative to 40:0h).
84h BYTE Maximum video text row.
85h WORD Height of EGA/MCGA/VGA character in scan lines.
87h BYTE Video EGA/VGA control byte.
88h BYTE Video EGA/VGA switches.
89h BYTE Reserved.
8Ah BYTE Video [MCGA/VGA]: index into display code table.
8Bh BYTE Diskette media control byte:
Bits [7:6] = Data rate used during last operation:
00 = 500 KB/second
01 = 300 KB/second
10 = 250 KB/second
11 = Reserved
Bits [5:4] = Diskette step rate used during last operation
Bits [3:0] = Reserved
8Ch
1
BYTE Last BIOS read of Fixed Disk Status register.
8Dh
1
BYTE Last BIOS read of Fixed Disk Error register.
8Eh
1
BYTE INT 13h IRQ semaphore.
8Fh BYTE Diskette controller information byte.
90h BYTE Diskette drive 0 media state (used internally by INT 13h diskette drive state machine).
91h BYTE Diskette drive 1 media state (used internally by INT 13h diskette drive state machine).
92h BYTE Diskette drive 0 media state at start of operation.
93h BYTE Diskette drive 1 media state at start of operation.
94h BYTE Diskette drive 0 current track number.
95h BYTE Diskette drive 1 current track number.
96h BYTE Extended keyboard status byte (1 of 2):
Bit 7 = 1 if a Read ID command is in progress
Bit 6 = 1 if last byte read was first of 2 ID bytes
Bit 5 = 1 force NumLock during Read ID command
Bit 4 = 1 if enhanced PC/AT keyboard installed
Bit 3 = 1 if right ALT key is pressed
Bit 2 = 1 if right CTRL key is pressed
Bit 1 = 1 if last byte read from KBC was E1h
Bit 0 = 1 if last byte read from KBC was E0h
Table 6-3. Format of the BIOS Data Area (Continued)
Offset Size Description