The IMSAI PIO 4 Rev-2 is a faithful reproduction of the 1975 PIO parallel I/O board.
The PIO 4-4 contains four independent 8-bit parallel input and output ports.
The output ports may be populated with the included LED lamps to provide visual indications of each bit state.
The PIO 4-4 is also available in a single-port version, the PIO 4-1. Port expansion kits are available to add ports to a PIO 4-1.
One novel feature of the PIO 4 was that is could occupy the first slot in a PCS-80 (IMSAI 8080) chassis and serve as a display-only front panel.
This configuration was never fully supported until now.
Front panel assemblies designed just for this purpose will be available for all IMSAI cabinets currently in the catalog.
When built to the instructions in the new User Manual, the PIO 4 is electrically and mechanically identical to the 1975 IMSAI PIO 4 Rev-2.
Order one from the list below. The kits are complete with everything you need except solder and tools unless otherwise stated.
They even come with a nice printed user manual. Be sure to hover over any
icons for more information.
| Description | Part Number | Availability | Unit Price (USD) |
PIO 4-1 Rev-2 complete kit with manual  | PIO 4-1-R | 7/15/2025 | $149.00 |
| PIO 4-4 Rev-2 complete kit with manual | PIO 4-4-R | 7/15/2025 | $229.00 |
Most builders won’t need anything else besides one of the above complete kits.
To skip over the options go to More Information to get links to useful resources.
If you're an advanced builder and want to see all the options, read on.
| Description | Part Number | Availability | Unit Price (USD) |
| PIO 4 internal cable, 50-pin card edge to two DB25-F | CABLE B | 6/30/2025 | $60.00 |
| Port expansion module for PIO 4-1 Rev-2 | PIO 4M-R | 7/15/2025 | $35.00 |
| Socket set for PIO 4-1 Rev-2, standard | SOC-PIO 4-1-R | 7/15/2025 | $5.00 |
| Socket set for PIO 4-4 Rev-2, standard | SOC-PIO 4-4-R | 7/15/2025 | $8.00 |
| Socket set for PIO 4-1 Rev-2, machined | SOCM-PIO 4-1-R | 7/15/2025 | $14.00 |
| Socket set for PIO 4-4 Rev-2, machined | SOCM-PIO 4-4-R | 7/15/2025 | $26.00 |
You may order a bare printed circuit board for you to use your own parts.
Be advised that individual parts are not available to bare board customers unless they are explicitly in the parts list below.