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 from the list below. The kits are complete with everything you need except solder and tools.
| Description | Part Number | Availability | Unit Price (USD) |
Port expansion module for PIO 4-1 Rev-2  | PIO 4M-R | In stock | $35.00 |
| Socket set for PIO 4-1 Rev-2, standard | SOC-PIO 4-1-R | 7/1/2025 | $5.00 |
| Socket set for PIO 4-4 Rev-2, standard | SOC-PIO 4-4-R | 7/1/2025 | $8.00 |
| Socket set for PIO 4-1 Rev-2, machined | SOCM-PIO 4-1-R | 7/1/2025 | $14.00 |
| Socket set for PIO 4-4 Rev-2, machined | SOCM-PIO 4-4-R | 7/1/2025 | $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.