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LOC OBJECT
0018 ??
0080
0040
0020
0010
0008
0019 77
001 A 7777
001C
????
00 IE (16
7777
)'"
LINE
SOURCE
(BIOS FOR THE I BM PERSONAL COMPUTER XT)
11/08/82
106
KB_FLAG
-
1
DB
SECOND BYTE OF KEYBOARD STATUS
107
108
INS SHIFT
EQU
80H
I NSERT KEY I S DEPRESSED
109
CAPS SHIFT
EQU
40H
CAPS LOCK KEY
I S DEPRE SSED
110
NUM SHIFT
EQU
20H
NUM LOCK KEY
I S DEPRESSED
111
SCROLL SH I FT
EQU
10H
SCROLL LOCK KEY
I S DEPRESSED
112
HOLD_STATE
EQU
08H
SUSPEND KEY HAS BEEN TOGGLED
113
114
ALT
INPUT
DB
7
STORAGE FOR ALTERNATE KEYPAD ENTRY
115
BUFFER HEAD
D¥f
7
PO I NTER TO HEAD OF KEYBOARD BUFFER
116
BUFFER-TA I L
OW
7
PO I NTER TO TA I L OF KEYBOARD BUFFER
117
KB_BUFFER
OW
i6 DUP(?)
ROOM FOR
15 ENTRIES
KB_BUFFER_END
LABEL
WORD
;------ HEAD = TAIL INDICATES THAT THE BUFFER
IS EMPTY
.
----------------------------------------
SEEK_STATUS
DB
DR I VE RECALl BRAT ION STATUS
BIT 3-0 = DRIVE 3-0 NEEDS RECAL
BEFORE NEXT SEEK
IF BIT IS = 0
DISKETTE DATA AREA S
DB
STATUS BYTES FROM NEC
T I ME OUT COUNTER FOR DR I VE TURN OFF
2 SECS OF COUNTS FOR MOTOR TURN OFF
RETURN CODE STATUS BYTE
ATT ACHMENT FA I LED TO RESPOND
SEEK OPERA T I ON FA I LED
NEC CONTROLLER HA S F A I LED
BAD CRC ON 0 I SKETTE READ
ATTEMPT TO DMA ACROSS 64K BOUNDARY
DMA OVERRUN ON OPERA T I ON
REQUESTED SECTOR NOT FOUND
WR I TE ATTEMPTED ON WR I TE PROT 0 I SK
ADDRESS MARK NOT FOUND
BAD COMMAND PASSED TO 0 I SKETTE I/O
I NTERRUPT OCCURRENCE FLAG
MOTOR STATUS
BIT 3-0 = DRIVE 3-0
IS CURRENTLY
RUNNING
BIT 7 = CURRENT OPERATION I S A WR I TE.
REQU I RES DELA Y
SCAN CODE FOR NUMBER LOCK
SCROLL LOCK KEY
AL TERNATE SH I FT KEY SCAN CODE
SCAN CODE FOR CONTROL KEY
SCAN CODE FOR SH I FT LOCK
SCAN CODE FOR LEFT SH I FT
SCAN CODE FOR RIGHT SH I FT
SCAN CODE FOR
I NSERT KEY
SCAN CODE FOR DELETE KEY
7
37
7
80H
40H
20H
10H
09H
08H
04H
03H
02H
01H
7 DUP(?)
080H
7
69
70
56
29
58
42
54
82
83
DB
EQU
EQU
DB
EQU
EQU
EQU
EQU
EQU
EQU
EQU
EQU
EQU
MOTOR COUNT
MOTOR=WA I T
DISKETTE STATUS DB
T I ME OUT-
EQU
BAD SEEK
EQU
BAD-NEC
EQU
BAD-CRC
EQU
DMA-BOUNDARY
EQU
BAD-DMA
EQU
RECORD NOT FND
EQU
WR I TE PROTECT
EQU
BAD ADDR MARK
EQU
BAD=CMD -
EQU
INT FLAG
MOTOR_STATUS
NUM KEY
SCROLL KEY
AL T KEY
CTL-KEY
CAPS KEY
LEFT-KEY
RIGHT KEY
INS KEY
DEL=KEY
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
0045
0046
0038
0010
003A
002A
0036
0052
0053
0041
77
0080 '
0040
0020
0010
0009
0008
0004
0003
0002
0001
0042
(7
77
j'
0040 ??
0025
0080
003F ??
003E ??
003E
162
163
• ----------------------------------------
164
V IDEO 0 I SPLA Y OAT A AREA
165
• ----------------------------------------
166
CRT MODE
DB
7
CURRENT CRT MODE
167
CRT-COLS
OW
7
NUMBER OF COLUMNS ON
SC~EEN
168
CRT-LEN
OW
7
LENGTH OF REGEN I N BYTES
169
CRT-START
OW
7
STARTING ADDRESS
IN REGEN BUFFER
170
CURSOR_POSN
OW
8
DUP (?)
CURSOR FOR EACH OF UP TO 8 PAGES
SYSTEM DATA AREA
FIXED DISK DATA AREAS
CURRENT CURSOR MODE SETT I NG
CURRENT PAGE BE I NG 0 I SPLA YEO
BASE ADDRESS FOR ACT I VE 0 I SPLAY CARD
CURRENT SETT I NG OF THE 3X8 REG I STER
CURRENT PALETTE SETT I NG COLOR CARD
LOW WORD OF T I MER COUNT
• HIGH WORD OF T I MER COUNT
;
T I MER HAS ROLLED OVER SINCE LAST READ
4 DUP(?)
OW
DB
OW
DB
DB
PR I NTER AND RS232 T I ME-OUT VAR I ABLES
OW
OW
TIMER DATA AREA
·
----------------------------------------
TIMER LOW
OW
7
TIMER-HIGH
OW
7
T I MER-OFL
DB
7
; COUNTS SEC
EQU
18
; COUNTS-M I N
EQU
1092
; COUNTS-HOUR
EQU
65543
; COUNTS=DAY
EQU
1573040 =
1800BOH
·
------------------------------------------------------
PR I NT_ T I M_OUT
DB
4 DUP ( ? )
·
----------------------------------------
BIOS BREAK
DB
; BIT 7=1
IF BREAK KEY HAS BEEN HIT
RESET_FLAG
OW
; WORD= 1234H I F KEYBOARD RESET UNDERWAY
·
----------------------------------------
io
ROM INIT
OW
; PNTR TO OPTIONAL
I/O ROM INIT ROUTINE
10-ROM-SEG
OW
; PO I NTER TO 10 ROM SEGMENT
INTR_FLAG
DB
; FLAG TO INDICATE AN INTERRUPT HAPPEND
POST DATA AREA
CURSOR MODE
ACT I VE-PAGE
ADDR 6845
CRT MODE SET
CRT=PALETTE
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
20 I
202
203
204
205
206
207
208
006C 7777
006E
7777
0070
??"
007177
0072
??71
0074 7777
0076
????
0078
(4
77
)'
007C
(4
77
)'
0049 77
004A
7777
004C
????
004E 7777
0050
(8"
7777
) ' "
0060 7777
0062 77
0063
??71
0065 77
0066
??
0067 7777
0069
????
006B ??
5-114
PC-XT System BIOS (11/08/82)
- Quick Links:
- Section 1. System Board
- 64/256K System Board
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