SpritesMind.Net

Sega Pico is Sega's toy with hardware similar to Genesis/MegaDrive. Recently some prototype ROMs appeared for it, and I've done some work on emulating them. The result is this little document and this little emulator. What I have problems with is figuring out what kind of PCM format Pico is using. ...

Nemesis wrote:The slots have a regular spacing of what appears to be a 2-cell period.

Yeah, it seems VDP does some additional processing every 2 cells, that's why we have 2-cell vscroll too.

I suspect the CPU core probably just handled cc being true or false without handling the count condition. I can confirm original Musashi handles all 3 cases correctly (i.e. the way docs say). But I think it has somthing to do with trace feature of 68k (trace exceptions). I think that is not being e...

HardWareMan wrote:2 AamirM: Author of that Gens Debugger Mod sends me the sources. Where I should send its? (You can tell me your email in PM).

You should post them here for us all to see

Wen you load your variables, you load them as words, including gravity: ROM:00000380 loc_380: ROM:00000380 move.w 0(a0),d7 ROM:00000384 move.w 2(a0),d6 ROM:00000388 move.w 4(a0),d5 ROM:0000038C move.w $C(a0),d2 But you save your gravity as byte: ... ROM:00000448 move.w d5,4(a0) ROM:0000044C move.b d...

Sik wrote:it initializes all VDP registers to 0 (as the real hardware)

Are you sure about that? I've seen that Fusion uses some non-zero initial values. Never checked the real hardware though.

And you're wrong too, what you mean with "interrupt 3" is "interrupt request 3" (IRQ3). Interrupt and exception are the same thing in this case. People tend to say interrupt when talking about an expected trigger and exception when talking about an unexpected one (errors), but they're interchangeab...

Fusion does not have it. Otherwise Tiido's program would detect it as real hardware. Hmm.. But Address Error exception is working. In debugger mode, when step by step running programm trying read word at odd address and goes at Address Error exception vector. Fusion has a debugger?? Fusion does not...

First of all tell me what difference will it make if I had opened up the source? Well, since you asked ... my argument is that it helps other aspiring emulator authors out. When I wrote my emulator, existing source code was a great source for research where the documents were not clear. Even luckie...

About the source code, well its not going to open up any time soon :( . When I am up to a point when I think I am done with it then I may consider open sourcing it. I can't understand your reason here. You have something to hide? BTW, it seems you are using the MAME YM2612 core, so by not releasing...

Stef wrote: I think i'll have a look on the source code to understand how this is possible, i though the SVP couldn't be dumped

It's simple - SVP uses the first 128K of game ROM for it's code, so there was no need to dump anything