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Update memory

august kline 2024-02-09 15:01:58 -05:00
parent 591a977acd
commit 601e39324c
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memory.md

@ -29,7 +29,7 @@ CPU Addressable
### 6845 crtc register interface at $4200 & $4201
when the system starts or when the video mode is changed, crt timing/character size information has to be sent to the 6845. This is done by writing to address `$4200` which internal register you want to access, then reading from or writing to address `$4201`. for example, this is how you would set the number of characters per row to 80:
when the system starts or when the video mode is changed, crt timing/character size information has to be sent to the 6845. This is done by writing to address `$4200` which internal register you want to access, then reading from or writing to address `$4201` (mostly writing to, all but four registers are write-only). for example, this is how you would set the number of characters per row to 80:
```asm
LDA #0 ;The "Horizontal Total" register is R0