10 OPEN1,8,2,"SCREENS.PAC,P,W"
20 SYS9*4096:.OPT O1:*=$8000
30 .ASC "PRO[195] MODE,PRO[195] CLEAR,PRO[195] PEN,PRO[195] LORES:PRO[199]:"
40 COL0 = 53281:COL1 = 53282:COL2 = 53283:COL3 = 53284:ZP1 = 254
50 JMP MOD:JMP CLR:JMP PN:JMP LRS
100 ; ********************
101 ; *** MODE COMMAND ***
105 MOD JSR $B79E:CPX #2:BCS ERROR:TXA:PHA:JSR $E200:CPX #2:BCS ERROR
110 PLA:STA 56576:TXA:EOR #1:ORA #40:STA 53272
115 TXA:ASL A:ASL A:ASL A:ASL A:ORA #8:STA 53270:LDA #59:STA 53265:RTS
130 ; *******************
131 ; *** (null) COMMAND ***
135 PN JSR $B79E:CPX #4:BCS ERROR:TXA:PHA:JSR $E200:PLA:TAY:TXA:STA 53281,Y:RTS
140 ; *** ILLEGAL QUANTITY ***
145 ERROR LDX #14:JMP $A43A
150 ; *********************
151 ; *** CLEAR COMMAND ***
160 CLR LDA 56576:AND #3:CMP #2:BCS ERROR
161 LDA 53270:AND #16:BEQ L162:JSR MCCLR
162 L162 JSR COLCLR
200 ; *** BITMAP CLEAR ***
205 ; ********************
210 LDA 56576:EOR #3:AND #3:SEC:ROR:ROR:ROR:STA L240+2:LDA #0:LDX #32
220 ; ** X PAGES -> A **
230 FILL LDY #0
240 L240 STA $0000,Y:INY:BNE L240:INC L240+2:DEX:BNE L240:RTS
300 ; *** FARBRAM CLEAR ***
310 ; *********************
330 COLCLR LDA 56576:AND #3:EOR #3:CLC:ROR:ROR:ROR
340 ORA #8:STA L240+2:LDX #4:LDA 53270:AND #16:BNE L344
342 LDA COL0:JMP L348
344 L344 LDA COL2:AND #15
348 L348 AND #15:STA VAR:LDA COL1:ASL A:ASL A:ASL A:ASL A:ORA VAR:JMP FILL
355 ; *** FARBRAM CLEAR $D8 ***
356 ; *************************
358 MCCLR LDA COL0:STA 53281:LDA #$D8:STA L240+2:LDA COL3:LDX #4:BNE FILL
790 ; *********************
791 ; *** LORES COMMAND ***
820 LRS LDA #$FF:STA 56576
830 LDA #4:STA 648:LDA #21:STA 53272
840 LDA 53265:AND #223:STA 53265:RTS
1000 VAR .BYTE 0
1020 .END:CLOSE1