Hardware Reference
In-Depth Information
Tabl e
1.14
(Continued)
Offset
Offset
BIOS
Field size
(hex.)
(dec.)
service
(bytes)
Function
69h
106
2
Adapter ROM segment address
6Bh
107
1
Last interrupt (not PC)
6Ch
111
Int 1Ah
4
Counter for Interrupt 1Ah
70c
112
Int 1Ah
1
Timer 24-h flag
71h
113
Int 16h
1
Keyboard Ctrl-Break flag
72h
115
POST
2
Soft reset flag
74h
116
Int 13h
1
Status of last hard disk operation
75h
117
Int 13h
1
Number of hard disk drives
76h
118
Int 13h
1
Hard disk control
77h
119
Int 13h
1
Offset address of hard disk I/O port (XT)
78h
120
Int 17h
1
Parallel port 1 timeout
79h
121
Int 17h
1
Parallel port 2 timeout
7Ah
122
Int 17h
1
Parallel port 3 timeout
7Bh
123
1
Parallel port 4 timeout support for virtual DMA services
7Ch
124
Int 14h
1
Serial port 1 timeout
7Dh
125
Int 14h
1
Serial port 2 timeout
7Eh
126
Int 14h
1
Serial port 3 timeout
7Fh
127
Int 14h
1
Serial port 4 timeout
80h
129
Int 16h
2
Starting address of keyboard buffer
82h
131
Int 16h
2
Ending address of keyboard buffer
84h
132
Int 10h
1
Number of video rows (minus 1)
85h
134
Int 10h
2
Number of scan lines per character
87h
135
Int 10h
1
Video display adapter options
88h
136
Int 10h
1
Video display adapter switches
89h
137
Int 10h
1
VGA video flag 1
8Ah
138
Int 10h
1
VGA video flag 2
8Bh
139
Int 13h
1
Floppy disk configuration data
8Ch
140
Int 13h
1
Hard disk drive controller status
8Dh
141
Int 13h
1
Hard disk drive error
8Eh
142
Int 13h
1
Hard disk drive task complete flag
8Fh
143
Int 13h
1
Floppy disk drive information
90h
144
Int 13h
1
Disk 0 media state
91h
145
Int 13h
1
Disk 1 media state
92h
146
Int 13h
1
Disk 0 operational starting state
93h
147
Int 13h
1
Disk 1 operational starting state
94h
148
Int 13h
1
Disk 0 current cylinder
95h
149
Int 13h
1
Disk 1 current cylinder
96h
150
Int 16h
1
Keyboard status flag 3
97h
151
Int 16h
1
Keyboard status flag 4
98h
155
4
Address of user wait flag pointer
9Ch
159
4
User wait count
A0h
160
1
User wait flag
A1h
167
7
Local area network (LAN)
A8h
171
4
Address of video parameter control block
ACh
239
68
Reserved
F0h
255
16
Intra-applications communications area
