| |
Fungus
Registered: Sep 2002
Posts: 617 |
REU and Color Memory
Can the REU access color memory or is it a quirk that it cannot?
I've not been able to get color memory scrolling to work with an REU and don't know if it's just a VICE bug or if this is intended. |
|
... 3 posts hidden. Click here to view all posts....
|
| |
Mr. SID
Registered: Jan 2003
Posts: 421 |
Sonic only writes to Screen and Color RAM, it never reads. Maybe reading doesn't work, I've never tried that... |
| |
tlr
Registered: Sep 2003
Posts: 1714 |
No point in speculating here. I'll ask on #vice-dev if someone knows if this is tested, otherwise we need to see what it does on a real machine. |
| |
chatGPZ
Registered: Dec 2001
Posts: 11116 |
it should work (ignoring that transfers from/to I/O are glitchy on some setups)
https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/REU..
And yes, for REU things use recent VICE :)
PS: make sure REU transfers do not start or end at the same cycle as VICII DMA, that causes weird behaviour/glitches. VICE does NOT emulate this correctly atm.
https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/REU..
https://sourceforge.net/p/vice-emu/code/HEAD/tree/testprogs/REU.. |
| |
Fungus
Registered: Sep 2002
Posts: 617 |
What do you mean by "some setups" ? |
| |
chatGPZ
Registered: Dec 2001
Posts: 11116 |
Random C64s, reason unknown. It may or may not be related to the (known) glitches that happen when REU DMA starts (or stops) at the same time as a VICII DMA. In some of those demos that show 1 pixel wide color splits using REU, you can see glitches - on some C64s. |
| |
Fungus
Registered: Sep 2002
Posts: 617 |
Okidoki, I'll check that REU is not dmaing at the same time then. |
| |
Martin Piper
Registered: Nov 2007
Posts: 634 |
Do you need to avoid bad lines? |
| |
Fungus
Registered: Sep 2002
Posts: 617 |
Yes, it can cause problems. Verified. |
| |
Repose
Registered: Oct 2010
Posts: 222 |
Quote: Okidoki, I'll check that REU is not dmaing at the same time then.
1 cycle is 8 pixels - how is a 1 cycle colour split done? |
| |
chatGPZ
Registered: Dec 2001
Posts: 11116 |
Simply DMA to a color register (with fixed target address) |
| Previous - 1 | 2 - Next |
