SpritesMind.Net

Oh, so you were trying to pause the disc while you went and did something else for a while and then unpaused it afterwords because you didn't have an exact 75 sector/second data rate? No wonder you were having speed problems. You're never going to get anywhere near full speed on the Sega CD CD-ROM d...

Depends on how accurate you want to be. A 68K at 12Mhz isn't fast enough to do accurate Z80 emulation in anything close to full speed. My thinking is that you might get at least a few games to run reasonably well if you cut some corners. Flag calculation is a real speed killer. When I was working on...

Forget to renew your domain?

So what do you have to do to "kick" the CDD?

Yeah, there is an interupt masker :) Perhaps messing with this will get you your results. There's certainly plenty of room for it to not work even if the problem is interupt related, but it's worth a shot. And yeah, i confirm that the CDC generate interupts every few ms... Yeah, every 1/75th of a s...

Out of curiousity, is the PCM chip being put to use already?

Is there some way to temporarily disable interrupt generation from the CDC? If I had to take a wild guess, I'd say that the CDC has problems if it doesn't get a proper IRQ acknowledgement and I would imagine that the 68K doesn't generate an IRQ ack signal when it's halted. Since the CDC (or whatever...

Are those made by Realtec? There are at least a few Realtec titles that don't work because they use a funny mapper despite the fact that they aren't big enough to need one. It appears to be an anti-piracy measure which is rather ironic since they also made cartridge copiers.

I think triggering an interupt on each write would be a lot slower than just accessing all data with the cache turned off. Interupt handling on the SH-2 takes a lot of cycles. What would probably make more sense is to set the processors up as part of a rendering pipeline in which the first processor...

I see... Maybe it was 4bit adpcm... I cannot check since it was rented game... If i remember correctly, the 32x documentation mentions that GEMS3.0 supports "Delta 4bit" DAC... I suspect it is a sort of adpcm-looking format specialy designed for the z80. Delta 4 bits is exactly the ADPCM 4 bits stu...

CAS latency has nothing to do with there being 2 processors on the bus it's a property of the RAM itself. Setting it to a lower value might work on some 32X units and it might not work on others or it might work on none of them as you'll probably be pushing the RAM chips out of spec. I was talking w...

Are you using DMA for your transfers? The 68K is so slow when it comes to doing memory access I would imagine it could become quite a bottleneck. I never quite got around to looking at how the various FMV enabled games did their DMA. I would imagine that you would need to get the DMA copy of the fir...

Umm, then we need to tell ppl to dont use hint... too complex to drive with accurency on segacd. If the demo is less than 53K or so, it's not complicated at all. Even if it's bigger than that, all you need to do is move the HInt handler to Genesis RAM. (i was too shocked by segacd hardware interupt...

Your advise is to use 68k for 4 tiles (128 bytes). But the CRAM is 128 bytes. So, to reload CRAM during active display, I could use 68k, couldn't I ? Depending on the situation, DMA can be useful for transfers as small as 16 bytes (8 CRAM entries). There's a fair bit of setup involved in preparing ...

Silpheed is the best looking 3D on the Genesis, but that is helped a lot by the Sega CD processor, I believe. Using the Sega CD, I wonder if the Sub CPU could handle all of the rotation and translation, and the Main CPU handle the rendering? I would imagine that it used the Sega CD graphics chip fo...