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.

I am a woman of my word. The Lego Game Boy - with a working Game Boy inside (not an emulator)

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.

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.

L’un des projets de modding les plus fous : la SEGA NEPTUNE ! Fusion d’une Megadrive et d’un 32X, cette console unique voit le jour grâce à @dvizix qui a créé la coque, et @cosam_the_great pour la partie électronique 🙏 La partie 2 arrive prochainement.... 🪐

I'm live, testing out how Sega CD games work via ROM carts on @cosam_the_great's Neptune. Come hang out if you're bored... https://t.co/E92nftu3qW

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!

Fixed! See this update:

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!

Sega Neptun boards with prepopulated birdseed are now available for order.

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 for the donor hardware, testing and troubleshooting.

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 for making this a reality. How awesome is this... Unreal! #SegaNeptune

Got my Neptune built and debugged. Genesis worked right away, but the 32x side took a while. I had several sneaky solder bridges I couldn’t see until I ultrasonic cleaned the board. Here’s a video of the final product. Thanks @cosam_the_great this rules! #neptune #genesis #32x

It's a busy 6-layer design, 4 signal, 1 ground, 1 VCC. Pretty advanced for the time.

Pretty niche this one, even for me. My non-running A530 started losing pads during troubleshooting, which was going slowly without schematics. Hopefully this will kill two birds with one stone.