mbandalauk wrote on 2025-10-29, 17:19:

Yeah, I was lucky to find my PCM-3370 SBC — it was actually headed for the skip when I spotted it in a pile of scrap boards. These things are quite expensive nowadays! I hope you manage to repair your board and get your adapter tested soon.

By the way, could I know the value of the L2 component on your backplane? While I was testing, a metal connector accidentally touched the gameport connector, and it blew the L2 inductor. Everything else seems to be working fine, but I assume the joystick will not function without that component.

Ouch! Ya, be careful! The way I had to organize the layers meant the top copper pour is all 5V. This is the main reason you need to use the isolation washers on top. L2 is the joystick 5V source and is needed to function. You could use a zero ohm jumper if you had nothing else, but the part is this ->https://www.digikey.com/en/products/detail/ta … 5HS250NT/957833, (25 Ohms @ 100 MHz 1 Power Line Ferrite Bead 0805 (2012 Metric) 6A 4mOhm).

Hi Tevian – Thank you. I will source that ferrite bead and repair my board.

I have been experiencing inconsistent behaviour with the PC/104+ adapter. My Voodoo 3 has always been slightly temperamental and sometimes freezes the system at random, so at first I assumed that was the cause. However, after testing several other graphics cards, they all show similar random freezes when used with the PC/104+ adapter. Even my FX 5500 freezes at times. All of these cards (except the Voodoo) work flawlessly when I use the PCISA-3716E2V with your backplane, which leads me to believe that the issue may relate to how I am using your PCI mapper card with the PC/104+ adapter.

To be fully transparent, I have not used the spare unpopulated PCI mapper board you sent me, because the populated one you provided worked perfectly with the PCISA-3716E2V setup. I have been using this same mapper with the PC/104+ adapter and my PCM-3370 SBC. Sometimes it works for a few minutes, and sometimes it freezes almost immediately. I am beginning to suspect that I may not be using the PCI mapper correctly in this configuration, particularly in relation to the IDSEL numbers I shared with you a few weeks ago. Could this be the root cause of the instability?

That's unfortunate... Since my working PCM module is slightly different in routing, this may need some trouble shooting on your part. I'm typing this mobile, so forgive me...

From what I can tell, the PCM-3370 (based on your probing), is another unique case of differing IDSEL and PCI INIT routing.

For the PCI card to work, the IDSEL must be present. That is unless the card needs IRQ functions. In that case the INIT pins must be routed properly. In my testing, I had strange behavior with some graphics cards needing this IRQ function. And, in the case my ATI card, it would only work in PCI 1 and and not 0...

Regardless, looking at the numbers, the PCISA config is close but different. It's possible your cards can work in one slot but not the other. For instance, they both use IDSEL 20, but not for the same PCI slot, throwing off the INIT routing...

This is the config the mapper card has unless you changed it. https://github.com/MagicPhase/Backwards-DIY-B … pci-mapper-card

I'll have to sit and examine later, but based on the numbers you gave, the correct PCI Mapper card config should be using the standard INIT routing side (Not the ALT routing!) With the IDSEL jumpers set for 20 (Slot 1) and 21 (Slot 2), instead of 19 (Slot 1) and 20 (Slot 2). Important to note, my board is marked (PCI 0 and 1) vs (1 and 2) just to make things complicated. So, you can try to modify the PCISA mapper by only changing the IDSEL pins to match the ones you discovered for your PCM module. Give that a try and let me know.

Oh! And it's important you set the PCI VI/O to 5V! It should be a jumper on you PCM module!