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fvdhoef / vera-module

Versatile Embedded Retro Adapter
MIT License
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Add option to disable PSG/Pal/Sprite in VRAM space #9

Closed mist64 closed 2 years ago

mist64 commented 2 years ago

Because the PSG/Pal/Sprite registers overlap with the top 1.5 KB of VRAM, this space is effectively unusable for graphics data. I am suggesting having a bit in CTRL turn on and off access to PSG/Pal/Sprite. This way, applications can use all 128 KB of VRAM by turning off this area temporarily.

fvdhoef commented 2 years ago

The 1.5KB of VRAM isn't unused, it is used to store a copy of the PSG/PAL/Sprite registers so they can be read back by the application.

mist64 commented 2 years ago

Oooooh, the VERA docs suggested otherwise. Thanks.