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retroclouds

TI Basic move crunch buffer in assembly

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22 hours ago, Asmusr said:

Further on the dependence on the F18A, you could add a horizontal scanline handler that changes the name table when it reached a certain scan line and changes it back again when the last line is reached.

 

Quick question on that. Do we have sample code showing how to use the scanline handler. I guess you basically load a short program on the F18A GPU and then set the start address in one of the VDP registers?

 

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40 minutes ago, retroclouds said:

 

Quick question on that. Do we have sample code showing how to use the scanline handler. I guess you basically load a short program on the F18A GPU and then set the start address in one of the VDP registers?

 

I don't have a generic example, but you can find everything in this code from zqx-one.

When you enable to hsync trigger it will start the GPU at it's current PC at the end of each scanline. The GPU will then run until it meets an IDLE instruction.

I'm setting up the hsync trigger every time the gpu code is called but you only have to set it up once.

From GPU code the VDP registers are mapped to >6000-603f. 

[Edit: registers are at >6000, current scanline is at >7000]

 

gpu.a99

Edited by Asmusr
Correction
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