Apple II User Manual
F820: C8 119 INY ; NO, INC INDEX (X-COORD)
F821: 20 0E F8 120 JSR PLOT1 ;PLOT NEXT SQUARE
F824: 90 F6 121 BCC HLINE1 ;ALWAYS TAKEN
F824: 90 F6 121 BCC HLINE1 ;ALWAYS TAKEN
F826: 69 01 122 VLINEZ ADC #$01 ;NEXT Y-COORD
F828: 48 123 VLINE PHA ; SAVE ON STACK
F828: 48 123 VLINE PHA ; SAVE ON STACK
F829: 20 00 F8 124 JSR PLOT ; PLOT SQUARE
F82C: 68 125 PLA
F82C: 68 125 PLA
F82D: C5 2D 126 CMP V2 ;DONE?
F82F: 90 F5 127 BCC VLINEZ ; NO, LOOP
F82F: 90 F5 127 BCC VLINEZ ; NO, LOOP
F831: 60 128 RTS1 RTS
F832: A0 2F 129 CLRSCR LDY #$2F ;MAX Y, FULL SCRN CLR
F832: A0 2F 129 CLRSCR LDY #$2F ;MAX Y, FULL SCRN CLR
F834: D0 02 130 BNE CLRSC2 ;ALWAYS TAKEN
F836: A0 27 131 CLRTOP LDY #$27 ;MAX Y, TOP SCREEN CLR
F836: A0 27 131 CLRTOP LDY #$27 ;MAX Y, TOP SCREEN CLR
F838: 84 2D 132 CLRSC2 STY V2 ;STORE AS BOTTOM COORD
133 ; FOR VLINE CALLS
133 ; FOR VLINE CALLS
F83A: A0 27 134 LDY #$27 ;RIGHTMOST X-COORD (COLUMN)
F83C: A9 00 135 CLRSC3 LDA #$00 ;TOP COORD FOR VLINE CALLS
F83C: A9 00 135 CLRSC3 LDA #$00 ;TOP COORD FOR VLINE CALLS
F83E: 85 30 136 STA COLOR ;CLEAR COLOR (BLACK)
F840: 20 28 F8 137 JSR VLINE ;DRAW VLINE
F840: 20 28 F8 137 JSR VLINE ;DRAW VLINE
F843: 88 138 DEY ;NEXT LEFTMOST X-COORD
F844: 10 F6 139 BPL CLRSC3 ;LOOP UNTIL DONE
F844: 10 F6 139 BPL CLRSC3 ;LOOP UNTIL DONE
F846: 60 140 RTS
F847: 48 141 GBASCALC PHA ;FOR INPUT 000DEFGH
F847: 48 141 GBASCALC PHA ;FOR INPUT 000DEFGH
F848: 4A 142 LSR
F849: 29 03 143 AND #$03
F849: 29 03 143 AND #$03
F84B: 09 04 144 ORA #$04 ; GENERATE GBASH=000001FG
F84D: 85 27 145 STA GBASH
F84D: 85 27 145 STA GBASH
F84F: 68 146 PLA ; AND GBASL=HDEDE000
F850: 29 18 147 AND #$18
F850: 29 18 147 AND #$18
F852: 90 02 148 BCC GBCALC
F854: 69 7F 149 ADC #$7F
F854: 69 7F 149 ADC #$7F
F856: 85 26 150 GBCALC STA GBASL
F858: 0A 151 ASL
F858: 0A 151 ASL
F859: 0A 152 ASL
F85A: 05 26 153 ORA GBASL
F85A: 05 26 153 ORA GBASL
F85C: 85 26 154 STA GBASL
F85E: 60 155 RTS
F85E: 60 155 RTS
F85F: A5 30 156 NXTCOL LDA COLOR ;INCREMENT COLOR BY 3
F861: 18 157 CLC
F861: 18 157 CLC
F862: 69 03 158 ADC #$03
F864: 29 0F 159 SETCOL AND #$0F ;SETS COLOR=17*A MOD 16
F864: 29 0F 159 SETCOL AND #$0F ;SETS COLOR=17*A MOD 16
F866: 85 30 160 STA COLOR
F868: 0A 161 ASL ;BOTH HALF BYTES OF COLOR EQUAL
F868: 0A 161 ASL ;BOTH HALF BYTES OF COLOR EQUAL
F869: 0A 162 ASL
F86A: 0A 163 ASL
F86A: 0A 163 ASL
F86B: 0A 164 ASL
F86C: 05 30 165 ORA COLOR
F86C: 05 30 165 ORA COLOR
F86E: 85 30 166 STA COLOR
F870: 60 167 RTS
F870: 60 167 RTS
F871: 4A 168 SCRN LSR ;READ SCREEN Y-COORD/2
F872: 08 169 PHP ;SAVE LSB (CARRY)
F872: 08 169 PHP ;SAVE LSB (CARRY)
F873: 20 47 F8 170 JSR GBASCALC ;CALC BASE ADDRESS
F876: B1 26 171 LDA (GBASL),Y ;GET BYTE
F876: B1 26 171 LDA (GBASL),Y ;GET BYTE
F878: 28 172 PLP ;RESTORE LSB FROM CARRY
F879: 90 04 173 SCRN2 BCC RTMSKZ ;IF EVEN, USE LO H
F879: 90 04 173 SCRN2 BCC RTMSKZ ;IF EVEN, USE LO H
F87B: 4A 174 LSR
F87C: 4A 175 LSR
F87C: 4A 175 LSR
F87D: 4A 176 LSR ;SHIFT HIGH HALF BYTE DOWN
F87E: 4A 177 LSR
F87E: 4A 177 LSR
F87F: 29 0F 178 RTMSKZ AND #$0F ;MASK 4-BITS
F881: 60 179 RTS
F881: 60 179 RTS
F882: A6 3A 180 INSDS1 LDX PCL ;PRINT PCL,H