Search found 81 matches

by Graz
Thu Dec 11, 2008 10:56 pm
Forum: Hardware
Topic: ROM Emulation
Replies: 86
Views: 30100

ROM Emulation

I want to share something that I've been toying with for a few days that I finally got working today. I picked up a ROM emulator off eBay for about $80 and have been building my own target cables for Genesis. The emulator I got was a PromICE P2160-35 and contains 4 megabytes of SRAM. It can emulate ...
by Graz
Thu Dec 11, 2008 3:26 pm
Forum: Tools
Topic: Kega Fusion v3.61
Replies: 44
Views: 20567

Re: Kega Fusion v3.6

King Of Chaos wrote:Lots of really bad things have happened, often working on Kega felt like the last thing I wanted to be doing.
That doesn't sound good. Hopefully things are going better for you now. We all appreciate the work you've done. Thanks, Steve.
by Graz
Wed Dec 10, 2008 5:06 pm
Forum: Sound
Topic: Z80 NMI
Replies: 9
Views: 3767

Mirroring usually occurs because of incomplete address decoding. As the Genesis only has (documented) registers at A11000, A11100, and A11200, it makes me wonder what, if anything, might be at A11300. If wrapping occurs, there's probably a mirror of A11000 at A11400, leaving a convenient gap at A113...
by Graz
Wed Dec 10, 2008 12:47 am
Forum: Sound
Topic: Z80 NMI
Replies: 9
Views: 3767

That's interesting. I wonder if there is any way to programatically generate an NMI from the 68K. Has anyone ever probed the undocumented area above A11200? It makes sense that if Sega were to plan such a feature, that is where the register would be. For example, what happens when a write is perform...
by Graz
Tue Dec 09, 2008 4:53 pm
Forum: Sound
Topic: Z80 NMI
Replies: 9
Views: 3767

If I understand correctly, on a real SMS the NMI is generated in hardware by the pause button. This button is not present on the genesis, but is on the power base converter. Then, the power base converter grounds M3 to signal SMS compatibility mode. You say that A23 is used for pause. Does the pause...
by Graz
Tue Dec 09, 2008 12:57 am
Forum: Sound
Topic: Z80 NMI
Replies: 9
Views: 3767

Z80 NMI

Does anyone know what generates an NMI on the Z80? According to the schematics I have, it's connected to the VDP (pin 70, labeled /NMI). However, I can't find the Z80's NMI mentioned in any documentation, and none of the ROMs I've looked at have a handler at 66h, suggesting that it can at least be d...