Re: Data Becker CBM-8000 hi-res graphics

Here in the clear screen subroutine you can see how the graphics ram access
works through these three extra decodeed registers:

CMD03:				        * clear graphics screen *
910B: A9 00     LDA #$00          * 00 = graphics value to store *                  
910D: A2 07     LDX #$07	        * graphics ram address pointers init -
starts at 0008 *                          
910F: A0 00     LDY #$00                          
9111: 8C 88 E8  STY $E888	* E888 = hi byte of address in graphics ram *
;
L_9114:
9114: E8        INX		        * increase lo byte of address pointer *                                  
9115: D0 04     BNE L_911B                        
9117: C8        INY                               
9118: 8C 88 E8  STY $E888	* increase hi byte of address pointer *                         
;
L_911B:
911B: 8E 82 E8  STX $E882	* E882 = lo byte of address in graphics ram *                         
911E: 8D 8A E8  STA $E88A	* E88A = value to store *                         
9121: E0 8F     CPX #$8F                          
9123: D0 EF     BNE L_9114                        
9125: C0 3E     CPY #$3E	        * graphics ram ends at 3E8E *                          
9127: D0 EB     BNE L_9114                        
9129: A9 80     LDA #$80	        * store 80 in 3E8F (non inverted screen?)*                          
912B: 8D 88 E8  STA $E888                         
912E: 60        RTS  



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