Search found 2364 matches

by TmEE co.(TM)
Sun Aug 04, 2019 1:07 pm
Forum: Sound
Topic: Looking for latest GEMS
Replies: 29
Views: 9587

Re: Looking for latest GEMS

For now I'm really busy with other things but eventually I could wire up the chips to a counter and record the outputs and give the dump of that, assuming it will be necessary. I don't think the chips do anything more than address decode stuff and their function should be easy to guess. I also tried...
by TmEE co.(TM)
Sun Aug 04, 2019 11:06 am
Forum: Sound
Topic: Looking for latest GEMS
Replies: 29
Views: 9587

Re: Looking for latest GEMS

I have dumped the GALs and the labelled chip and unfortunately the GALs seem to be protected, fusemap reads as all ones, with ID bits giving a pattern. But the labelled chip does look like a good dump. In addition I stripped most parts off the cart and took some photos that should be good enough for...
by TmEE co.(TM)
Wed Jul 17, 2019 11:34 pm
Forum: Controls
Topic: Mega Mouse unused nibbles research
Replies: 30
Views: 1392

Re: Mega Mouse unused nibbles research

There's also the question of why the Nomad doesn't take the Sports Pad… but then again, I recall hearing it doesn't like the link cable in Zero Tolerance? (ironically, since two Nomads would have been the perfect way to use it) Not sure how true is that but I wouldn't be surprised if there's someth...
by TmEE co.(TM)
Tue Jul 09, 2019 2:17 am
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 45
Views: 6812

Re: Cart Design Questions

You should use multiple vias for the power traces whenever possible. Looking good otherwise ~
by TmEE co.(TM)
Tue Jun 18, 2019 9:39 pm
Forum: Sound
Topic: How DAC works ?
Replies: 8
Views: 601

Re: How DAC works ?

YM2612 outputs for one cycle every 6 cycles (one channel time), while YM3438 output at 5 (at least I recall gaps between each channel) of these 6 cycles IIRC. This gives 3438 much better SNR and also makes it need much less amplification and easier filter to get good output level compared to 2612. T...
by TmEE co.(TM)
Mon Jun 10, 2019 6:32 pm
Forum: Mega/SegaCD
Topic: Japanese MegaCD BIOS 1.00C
Replies: 1
Views: 321

Japanese MegaCD BIOS 1.00C

I was given a chance to dump a new Mega CD BIOS, Japanese version 1.00C and here it is :
http://www.tmeeco.eu/SMD/BIOS/MegaCD%20J%201.00C.BIN
Image
by TmEE co.(TM)
Tue Jun 04, 2019 10:16 am
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 114
Views: 9542

Re: Questions on writing a new Mega CD emulator

The big filters are for bandwidth limiting and are responsible for the characteristics of the passband ripple and whatever goes on in the stopband. This isn't really useful to model, especially since whatever plays the sound will do its own stuff like that, mangling whatever you did (and you need to...
by TmEE co.(TM)
Wed May 22, 2019 12:39 pm
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 5947

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

It actually is connected, just on VA0 32X. on VA1 it is replaced with GND connection on the cartridge end. I wonder why...
by TmEE co.(TM)
Wed May 22, 2019 8:18 am
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 5947

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

Write strobe is passed but in only works from accesses from 68K side, SH2s can only produce read cycles in cart area. I don't know if this is a limitation due to bus management chip or SH2 configuration registers caused problem. You're not supposed to change those registers after initial setup but I...
by TmEE co.(TM)
Tue May 21, 2019 1:50 pm
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 5947

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

That's good to know, another mod to add to a 32X to make it more useful. Just need to figure out how exactly should overriding stuff work lol
by TmEE co.(TM)
Mon May 20, 2019 9:49 pm
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 5947

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

Then I remember wrong. I recall that it used one such area that 32X didn't pass through and possibly used it for itself thus SVP cannot run through it but seems only A15xxx range is used by SVP outside normal stuff. But it could just be the DMA latency issue I just read about from your docs. 32X doe...
by TmEE co.(TM)
Sun May 19, 2019 10:50 am
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 45
Views: 6812

Re: Cart Design Questions

You can use !AS to latch the current address for decode purposes etc. I'm not sure if DMA uses it or not though.
by TmEE co.(TM)
Sat May 18, 2019 7:39 pm
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 5947

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

It can only be used in ranges where VDP doesn't generate it for you such as 800000...9FFFFF. This area is used by 32X and SVP for example. You cannot forcibly override !DTACK since VDP actively drives it on most accesses.
by TmEE co.(TM)
Sat May 18, 2019 7:37 pm
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 45
Views: 6812

Re: Cart Design Questions

You can only drive !DTACK in 800000...9FFFFF range and other ranges (holes in IO ranges) where it isn't generated by VDP for you. In ranges where it is you will cause contention and that's gonna destroy something sooner or later.