Atari 400 Technical Reference Manual page 292

ERR LINE AD DR B1 B2 B3 B4
INTERRUPT HANDLER PAGE 31
1261
· PAGE
1262
1263
IRG HANDLER
1264
1265
JUMP THRU IMMEDIATE IRG VECTOR, WHICH ORDINARILY POINTS TO
1266
SYSTEM IRG: DETERMINE
.&
CLEAR CAUSE, JUMP THRU SOFTWARE VECTOR.
1267
1268
*=INTORG
1269 E6D5
A9 40 IHINIT: LOA *$40
iVBL ON BUF DLIST OFF***FOR NOW***
1270 E6D7 SD OE D4
STA NMIEN iENABLE DISPLAY LIST, VERTICAL BLANK
1271 E6DA
A9 38 LOA #$38 iLOOK AT DATA DIRECTION REGISTERS IN PIA
1272 E6DC
80 02 D3 STA PACTL
1273 E6DF 80 03 D3
STA PBCTL
1274 E6E2
A9 00 LOA #0 iMAKE ALL INPUTS
1275 E6E4
80 00 03 STA PORTA
1276
E6E7 80 01 D3 STA PORTB
1277 E6EA A9 3C LDA #$3C
iBACK TO PORTS
1278 E6EC 80 02 D3 STA
PACTL
1279
E6EF SD 03 D3 STA PBCTL
1280 E6F2 60
RTS
1281 E6F3 6C 16 02 PIRG: JMP (VIMIRG)
12S2 E6F6 SO CMPTAB: · BYTE $80 iBREAK KEY
1283 E6F7 40
· BYTE
$40
i
KEY STROKE
1284 E6F8 04
· BYTE
$04
i
TIMER 4
12S5 E6F9
02
· BYTE
$02
i
TIMER 2
1286 E6FA 01
· BYTE
$01
i
TIMER 1
1287 E6FB 08
· BYTE
$08
iSERIAL OUT COMPLETE
1288 E6FC 10
· BYTE
$10
iSERIAL OUT READY
1289 E6FD 20
· BYTE
$20
i
SERIAL IN READY
1290 E6FE
1291
i
THIS IS A TABLE OF OFFSETS INTO PAGE 2. THEY POINT TO
1292 E6FE
36 ADRTAB: · BYTE BRKKY-INTABS
1293 E6FF 08
· BYTE
VKEYBD-INTABS
1294 E700
14
· BYTE
VTIMR4-INTABS
1295 E701
12
· BYTE
VTIMR2-INTABS
1296
E702 10
· BYTE
VTIMR1-INTABS
1297
E703 OE
· BYTE
VSEROC-INTABS
1298 E704 OC
· BYTE VSEROR-INTABS
1299 E705 OA
· BYTE
VSERIN-INTABS
1300 E706
1301 E706 48
SYIRG: PHA iSAVE ACCUMULATOR
1302 E707
AD OE D2 LDA IRGST CHECK FOR SERIAL IN
1303 E70A
29 20 AND
*$20
1304 E70C
DO 00 BNE SYIRG2
1305 E70E A9 OF
LOA *$DF MASK ALL OTHERS
1306 E710 80 OE 02 STA IRGEN
1307 E713 A5 10
LOA POKMSK
1308 E715
80 OE D2 STA IRGEN
1309 E718
6C OA 02 JMP (VSERIN)
1310 E71B
SA SYIRG2: TXA iPUT X INTO ACC
1311
E71C 48 PHA
iSAVE X ONTO STACK
1312 E71D A2 06
LOX *$6 iSTART WITH SIX OFFSET
1313 E71F BD F6 E6
LOOPM: LOA CMPTAB,X ; LOAD MASK
1314
E722 EO 05 CPX
*5
iCHECK TO SEE IF COMPLETE IS SET