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6502 SBC

#11 · June 20, 2025, 5:24 am

Thanks.

That program seems to work ok for me:
It stores $FF at RAM $2000 and $AA at $2001

8000   AD 00 60             LDA $6000    ; // Read value at address $6000 (VIA) ACC = $FF
8003   8D 00 20             STA $2000    ; // Store ACC to address $2000 (RAM)
8006   A9 00                LDA #$00     ; // Load $00 to ACC
8008   85 80                STA $80      ; // Store ACC to address $80 (RAM)
800A   A9 20                LDA #$20     ; // Load $20 to ACC
800C   85 81                STA $81      ; // Store ACC to address $81 (RAM)
800E   A9 AA                LDA #$AA     ; // Load $AA to ACC
8010   A0 01                LDY #$01     ; // Load $01 to Y
8012   91 80                STA ($80),Y  ; // Store ACC to address stored in $80 $81 + Y = 2000 + 1

About IRQ and NMI I found at least one bug.
I think this was never tested, so probably more...

#12 · June 20, 2025, 6:46 am

Your right, sorry. stupid mistake from me. I compiled the complete memtest routine and it works great now, strange.

I will test :), should be fun if I can get microsoft basic or apple integer basic working on my real SBC, with some kind of serial communication. I can simulate all that with SimulIDE before I make it in real hardware. Some much fun.