megatron-uk wrote on 2023-01-11, 11:45:

Is there anything (except solder points for +5, +12, -12 and ground) to stop the use of a small ISA riser as a backplane for a sbc and one or two cards?

No.

It should work without problems. I have done the same things with a 486 SBC, added vga, a sound card and network.

i have use the Amiga4000 riser card in the same way, no problem. I think will be the same for you.

I've done this and it works, this particular SBC has super I/O and video integrated so the extra port is for the sound card.
I got an ISA single port angler, soldered another ISA connector onto the edge connector - along with the ATX connector from one of those 24pin to 20 pin ATX connectors that I sacrificed.

There's a little header for the on/off switch and the power wires were soldered onto bits of stripboard to add some strength.

I considered doing this to a 3 port ISA riser but didn't in the end because I don't like the idea of soldering onto the hard gold pins of the ISA header. Later I designed up a PCB to be a 3 port riser which simplifies the wiring significantly for SBCs:

Yeah - that 'shoebox' formfactor is exactly the sort of thing I am looking to achieve. Great stuff!

Did you 3d print the IO bracket holder or did you find a supplier?

It's all 3d printed with some wooden dowels to give some strength to it, since I had those laying around at the time. I didn't share the designs because the PCB design has a couple of flaws, specifically in that it didn't need to be 2 boards and the ATX connector is too close to the cards.
If you're interested though, I'd be happy to share them after I get a chance to fix them. I haven't thought much about this since 2020 when I got the 5x initial PCBs made 😀