9-Slot S-100 Motherboard with Integrated Power Supply (Bare PCB)

A compact S-100 backplane with on-board power generation - ideal for bench testing, diagnostics, and small vintage builds without the tangle of external supplies. This listing is for the bare printed circuit board only. No components, connectors, or power supply included. Photos with components are for illustration only to show completed board.

The design's headline feature is integrated power: rather than sourcing the S-100 bus's awkward voltages from separate bricks, V5 runs off a single 24V barrel-jack supply (15–29V works) and generates the +8V and ±16V rails on-board via three switch-mode regulator modules. The slightly conservative rail voltages sit well within tolerance for the per-card regulators every S-100 board carries.

Board features:

1. 9 S-100 slots with optional active termination for cleaner high-speed signaling
2. 3 on-board switching supplies
3. Power toggle, reset switch, and resettable fuses
4. 3-way jumpers on three legacy pins: ground, unterminated, or active-terminated
5. Termination-power enable jumper and indicator LED
6. Expansion / logic-analyzer hookups
7. Altair/IMSAI case mounting holes
8. Enlarged 0.042" edge-connector holes for easier hand assembly

Best suited to small bench systems - the intended regulator modules comfortably power 3-4 standard cards, so it's built for diagnostics and compact builds rather than a fully loaded rack. (Though in testing, I have added a fan to my 7.5V regulator and pushed it up to 8 boards without issue).

Open source, full design files, BOM, and a Mouser parts project are available on the project's GitHub page so you can source components and populate exactly what you need. A few parts (LM4250CN op-amp, slot connectors, 24V supply, regulator modules) are sourced separately from the main BOM. This is the latest (rev 2) version of the PCB.