We believe the problems we had were indeed noise-related. Getting them made with 4 layers (2 internal ground planes) should help with that. The -01 board is not much better and won't directly support MCE1 but could be workable if you check the differences in the schematic and adjust as necessary.
Poor designer
Debugging the SFC to CD mechacon interface. Timing to work out on the PLD side to get reliable reads/writes each way. The scope shows the individual nibbles of an ACCESS command being transferred to an ATMega microcontroller that's standing in for the real mechacon chip.
Some progress on the Nintendo PlayStation: some programmable logic acts as a bridge between SFC and CD hardware. Set up in a loopback configuration, the BIOS now thinks it's talking to the mechacon MCU. Mock firmware is ready to go once this part is debugged.
It's wired up exactly like it's connected via the expansion port so a standalone unit would work the same way. They probably thought about keeping that as a possibility.
Can't imagine anyone following me isn't following Bob already, but here's us chatting about hardware preservation, the Neptune and other such topics.
So cool to see these running in the wild and even better to see the community pitching in with support!
My @cosam-the-great.bsky.social Neptune board up and running! Shoutouts to the @retrorgb.bsky.social and @dubesinhower.bsky.social Discords for some troubleshooting at the end. By far the hardest project I've taken on. It's a shame tariffs have put a Neptune shell out of the budget :(
Haha, I'll let you have a crack at it too then and we can compare notes when you get going if you like. Only have a few hours in this so far.
If you don't manage to find one, this is coming along quite nicely...
Yeah man, I get it! writing code for current gen hardware at the time seemed almost mythical.
Nice, would be interesting to know what dev tools, etc. you're using to do this stuff and how one might get started on PS1.
To help with fixing the region flicker, i made a flex pcb.
github.com/Board-Folk/N...
ITYF that's totally a drill.
Minor update to the Neptune PCB, mostly to better support more donor revisions. Focus of the next release will be attempting to simplify and improve composite video. github.com/Board-Folk/N...
Neptune revision 1.4 has just been released, including the "region flicker" fix and some BOM updates/corrections. This one was a real team effort, so thanks to all who contributed! github.com/Board-Folk/N...
Fixed! See bsky.app/profile/cosa...
Credit to (GitHub users) dr-goobur for providing the elusive fix, supported by noobguy57, angelsix, v00dooperson and many more behind the scenes.
Thanks to the tireless efforts of the community, the Neptune "region flicker" issue has been diagnosed and fixed! To commemorate in true #Sega style, here's a service bulletin, complete with traditional inconsistent fonts and dodgy layout.
Neptune builders/users should be aware of this very weird issue. TLDR: a few games that actively access the region/version settings of the console display artifacts in certain mode combinations. If anyone has more ideas regarding the cause we're all ears! github.com/Board-Folk/N...
If you planned on building a #Neptune #SegaNeptune via @cosam-the-great.bsky.social’s board, you should seriously consider this pre-populated version, as it’ll make a really hard project a bit easier. Plus, Jan used great quality caps. Links and more info: www.retrorgb.com/neptune-pcb-...
PC Engine GT/TurboExpress main PCB repro is now public. If you have the skills and knowledge, there is still a lot to be identified on the schematic! Thanks again to @pointerfunction.bsky.social for the donor hardware, testing and troubleshooting. github.com/Board-Folk/P...
Woohoo! Nice work Dennis, now it's verified I'll be publishing the project any time now, including preliminary schematics.
Forgot all about publishing that one... Credit goes to @dshadoff.bsky.social for the original design github.com/Board-Folk/P...
"SCA only" means only fit if you have the SCA chip in the 32X. You basically want to copy what the donor has. For the caps, a small difference in height shouldn't be a problem.
Also the slowest ISA machine I have is a 486 with a 8 Mhz bus clock which is way too fast. Unused flip-flop on the board bodged in as a frequency divider brings it into spec 😅 Will try to work this into the board as a configurable option.
Reasonably convincing except for the lack of volume knob and ISA bracket. No actual audio coming out of it yet, I suspect my AliExpress special AY chips may not be 100% genuine...
It’s alive!!
Thanks @cosam-the-great.bsky.social for the awesome project. Definitely the hardest project I’ve ever attempted.
Nice work. And also @pointerfunction.bsky.social's favorite 32X game ever.
That's insane! And some decent games in there too.
