PIO 4 Rev-2

The IMSAI PIO 4 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 will be electrically and mechanically identical to the 1975 IMSAI PIO 4 Rev-2.

The PIO 4 is licensed for sale by IMSAI from RetroTechReboot. It is entirely produced and shipped by Parastream Technologies.

Order from the list below. Be advised that individual parts for the kit are not available to bare board customers unless they are explicitly in the options list. Please check the parts list.

PIO 4-1

Complete PIO 4-1 Rev-2 kit with printed user manual. A complete reproduction of the original 1975 IMSAI PIO 4-1 Rev-2 kit.

PIO 4-4

Complete PIO 4-4 Rev-2 kit with printed user manual. A complete reproduction of the original 1975 IMSAI PIO 4-4 Rev-2 kit.

PIO 4-BB

PIO 4 Rev-2 bare board.

You may also add one or more of these options to complete your build.

SOC-PIO 4-1

Standard socket set for PIO 4-1 Rev-2.

SOCM-PIO 4-1

Machined socket set for PIO 4-1 Rev-2.

SOC-PIO 4-4

Standard socket set for PIO 4-4 Rev-2.

SOCM-PIO 4-4

Machined socket set for PIO 4-4 Rev-2.

PIOM

Expansion input and output port kit with two 8212 chips and 8 LEDs.

SOC-PIOM

Standard socket set for an expansion input and output port kit.

SOCM-PIOM

Machined socket set for an expansion input and output port kit.

You may also add one or more of these accessories and parts.

CABLE B

14" flat cable connects PIO 4 input or output connector to cabinet rear frame.

Project Status

The PIO 4 Rev-2 development is scheduled for Q2 2025.