I just finished parity SIMM 72-pin design (just 2-layers to save money but pwr/gnd planes could be added in future if needed).
I plan to send a batch of PCBs to JLC until end of this month to get advantage of 2$ discount for 4L 50x50mm for PentiumMMX mobile interposer.

A new version of BlueSCSI has just been released, based on the Raspberry PI Pico (much faster - up to 10MB/s read). The software is derived from the ZuluSCSI project.
https://bluescsi.com/v2

I received my PCBs from JLCPCB and started assembly the SIMM module. At 1st test stage I soldered only 8 DRAMs of 12 and it works fine (memory tests passed, even it's only 2-layer design) but I found a mechanical problem. I didn't get aware of PCB thickness and now I see the original SIMM is 1.2mm thick PCB while I made all PCBs on JLC default thickness 1.6mm. The module fits into a socket but it's tight. Some sockets are relative OK some are very tight. I'm bit afraid of spring-pins to not deform them too much so I rather not left module in a socket for long time and pull it out. When I googled about this I found Alex. Groza article about his 30-pin SIMM and he catched at the same thing. If I would read his article (that I already had downloaded for offline reading) before I could order the proper PCB thickness...

So, never mind, the price for this PCBs was ~5,5$ and I use it for testing in my Alpha64 after I will solder the rest of DRAMs and set the ID bits. Then I will give another try in JLCPCB when there will be a chance or I will collect PCBs for a next batch...

Yes, I know. My first SIMMs in 1.6 mm thickness were a very frustrating experience for me as well. And exactly as you say, some of sockets do accept 1.6 mm PCBs but they look a bit stressed.
I re-did mine at JLCPCB in 1.2 mm, they work great and are a perfect fit for the SIMM sockets. On the downside, the black soldermask quality is not very good. The JLCPCB green one is better, similar to the purple soldermask from OSHPark.

Good job on your SIMM design! Glad to hear it works on a dual-layer PCB.

Cheers,

I soldered the rest of DRAM chips (I had to borrow them from another working parity module because I don't have any other donor now) and it works fine in Alpha64. So when possible I will let manufacture them again with right thickness.
I'm not a fan of black or white opaque solder mask, I like visible traces. So I usually keep default green mask, only once I made red.

There's 386 replica motherboard project now - https://github.com/Marco-Both/M396F-Replika

There's a someone by the name of rehsd that's making a 80286 homebrew pc. He plans to try to achieve dos 6.22 compatibility. One of the interesting things about this build is that he's not using any old vintage chipsets like past x86 homebrews have had. The chipset and bus control is done using modern components. It's way more work to make a homebrew x86 this way but performance boost from doing it this way would make it theoretically possible to run things like harris 25mhz 286's at their native speed. The thing preventing people from doing that type of thing on already existing 286 boards is that boards using chipsets capable of such speeds are extremely rare.

This isn't an actual project, but it's a project I'd like to see (maybe I should start a separate thread talking about it?)

I was just thinking of my frustration getting networking under DOS working on VirtualBox, and started thinking of how I could make space to put the 486 I keep putting off building because I don't have the desk space for it... and I just wished that I had a 486 or Pentium 1 on a card I could just plug into my modern PC and use its keyboard/video/mouse output.

Then I remembered the Bridgeboard for the Amiga, which was a PC on a card that plugged into the Amgia.

I don't know how PCI-e works, but it should be more than fast enough to support a 486 or pentium 1 -based PC emulator card. Like an old-fashioned SBC, it could have video, audio and i/o options on-board, or just use the host PC's.
The socket plate could have plugs for USB-C and/or a custom port into which an external ISA/PCI/AGP daughtercard could be connected to provide slots for cards providing abilities not built-in to the Bridge card, such as a Voodoo 2.
I'd prefer it to use an actual 486 or pentium 1, but I'm sure it would need an FPGA for some of the other services, such as I/O and video support. Maybe not?

I remember that some years ago I saw such PC card with 486 or Pentoum for old Apple computer that plugged in PCI slot. It allowed running native x86 apps. But I don't know how I/O was handled, if it was capable to render in a MacOS window. No idea if such card could also run in x86 PC under window, probably no due to lack of bridging drivers, reverse engineering would be needed.