Search found 860 matches

by Sik
Sat May 04, 2019 1:33 pm
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 112
Views: 7624

Re: Questions on writing a new Mega CD emulator

I'm gonna laugh if we end up redumping every single CD from scratch using a Mega CD/LD simply because it's capable of dumping all that. That's gonna get real expensive, real quick with the high and rapid failure rate of Sega CD hardware. I mean, we probably want to do maintenance on the mechanical ...
by Sik
Fri May 03, 2019 11:17 pm
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 112
Views: 7624

Re: Questions on writing a new Mega CD emulator

I'm gonna laugh if we end up redumping every single CD from scratch using a Mega CD/LD simply because it's capable of dumping all that. I'd strongly advise you ignore the abomination that is iso+mp3 though, and never support it. Make the user find at least a halfway decent image file to start with. ...
by Sik
Fri May 03, 2019 11:50 am
Forum: Super 32X
Topic: Using 32x as a 3rd plane, possible?
Replies: 28
Views: 3892

Re: Using 32x as a 3rd plane, possible?

It works on Kega Fusion, right now I'm trying to figure out what's going on. Maybe this program ignores RV, but is not that simple, I need more time. Fusion is not accurate :​O) Reminds me, Chaotix tries to show "DEVELOPED FOR USE ONLY WITH SUPER32X SYSTEMS." if you plug it into a MD directly witho...
by Sik
Fri May 03, 2019 2:09 am
Forum: Cartridge
Topic: Size limits
Replies: 35
Views: 7313

Re: Size limits

Yeah, but later we were discussing about this in Plutiedev and the mapper is always write-only while the 32X register is always read-only (meaning that in theory, it's perfectly possible there's no conflict simply because they don't respond to the same strobes). Sounds like we'll need to make some t...
by Sik
Thu May 02, 2019 4:15 pm
Forum: Sound
Topic: Some beginner questions concerning YM2612
Replies: 24
Views: 2664

Re: Some beginner questions concerning YM2612

Isn't decibels-to-linear something like pow(2,dB/6)? (in the case of attenuation the decibels would be negative) That returns a multiplier (in floating point), mind you, but should give you a clue of where to go.

I may or may not be misunderstanding your question.
by Sik
Thu May 02, 2019 4:09 pm
Forum: Cartridge
Topic: Size limits
Replies: 35
Views: 7313

Re: Size limits

Isn't 32X just masking this range? A130EC read (also write?) will just never make it to the cartridge, right? Yeah, that's what I said earlier, and I mentioned some games that use $A130F1 map all of $A130xx to it, and as far as I'm aware Sonic 3 (& Knuckles) doesn't have problems with the 32X despi...
by Sik
Thu May 02, 2019 4:02 pm
Forum: Super 32X
Topic: Using 32x as a 3rd plane, possible?
Replies: 28
Views: 3892

Re: Using 32x as a 3rd plane, possible?

We don't know if they ever got around to fixing the devkits actually, seeing as the docs we have predate the 32X's release. The scary part is that going by the tech bulletins (I was reading them the other day incidentally), they were still making revision changes to the hardware in September 1994. T...
by Sik
Thu May 02, 2019 3:57 pm
Forum: Cartridge
Topic: Size limits
Replies: 35
Views: 7313

Re: Size limits

Potential for bus fights.

But yeah, $A130EC is a 32-bit register that returns "MARS" when read and nothing else. Its only purpose is to allow detection of a 32X.
by Sik
Thu May 02, 2019 3:50 pm
Forum: Cartridge
Topic: Size limits
Replies: 35
Views: 7313

Re: Size limits

I thought the 32X caught the $A130EC-$A130EF range and passed along the rest (・~・) (since it can intercept anything that goes through the cartridge slot). Especially given the games that map all of $A130xx to what would be $A130F1 (so basically anything that saves and is larger than 2MB, or Sonic 3 ...
by Sik
Thu May 02, 2019 9:29 am
Forum: Cartridge
Topic: Size limits
Replies: 35
Views: 7313

Re: Size limits

Any chances to adapt it to use /TIME instead to switch banks? (・・?) I'd really prefer if we don't go around coming up with new schemes all over the place (the more standarized we can get the hardware, the easier it becomes to emulate it) Asking since I imagine that some people may want to use that b...
by Sik
Thu May 02, 2019 7:09 am
Forum: Super 32X
Topic: Using 32x as a 3rd plane, possible?
Replies: 28
Views: 3892

Re: Using 32x as a 3rd plane, possible?

I'm not. The vector ROM points to that table… in the mirror space (i.e. $880200, $880206, $88020C, etc.). That means when an interrupt happens, the 68000 will fetch those addresses and jump to the mirror, which won't respond since the 32X disabled it, and hence the 68000 will be stuck forever waitin...
by Sik
Thu May 02, 2019 6:23 am
Forum: Super 32X
Topic: Using 32x as a 3rd plane, possible?
Replies: 28
Views: 3892

Re: Using 32x as a 3rd plane, possible?

68k got stuck because the design they had as a whole simply couldn't scale much further, and any attempt at rearchitecting it would leave them in the dust, and everybody else was already switching to x86 anyway because PCs were already hogging the market (while the 68k machines were either all going...
by Sik
Thu May 02, 2019 6:14 am
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 112
Views: 7624

Re: Questions on writing a new Mega CD emulator

The big mystery to me is, how do regular CPU reads and writes work? If it's really just the work RAM being slow, wouldn't it take just a touch too long to respond to regular reads as well? And even in the case of DMA, won't the address lines get incremented before the read completes? And won't that...
by Sik
Thu May 02, 2019 5:19 am
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 112
Views: 7624

Re: Questions on writing a new Mega CD emulator

Man, I keep thinking this system can't get any flakier and yet it keeps managing to impress me. I have no clue how to emulate this cleanly. I can't implement it as a one-time action inside writes to VDP register 1 (which sets the DMA enable flag), because it seems like other DMA registers get writt...
by Sik
Wed May 01, 2019 8:34 pm
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 112
Views: 7624

Re: Questions on writing a new Mega CD emulator

I recall it's a timing issue (word RAM is too slow and the DMA hardware has zero notion of paying attention to the bus signals, which in itself has caused other problems). Virtua Racing (SVP) has a similar issue with the SVP RAM if I remember correctly. I'll try to see where in the docs this is ment...