The IMSAI SIO 2 Rev-3 is a faithful reproduction of the 1975 SIO USART board.
The SIO 2 is available in a one-port (SIO 2-1) or a two-port (SIO 2-2) configuration.
Each port is a complete synchronous/asynchronous USART (8251A) with TTL, RS-232, and current loop interfaces.
A port expansion kit is available to convert an SIO 2-1 to an SIO 2-2.
When built to the instructions in the new User Manual,
the SIO 2 is electrically and mechanically identical to the 1975 IMSAI SIO 2 Rev-3.
Order from the list below. The kits are complete with everything you need except solder and tools.
| Description | Part Number | Availability | Unit Price (USD) |
Socket set for SIO 2-1 Rev-3, standard | SOC-SIO 2-1-R | 7/1/2025 | $9.00 |
| Socket set for SIO 2-1 Rev-3, machined | SOCM-SIO 2-1-R | 7/1/2025 | $28.00 |
| Socket set for SIO 2-2 Rev-3, machined | SOCM-SIO 2-2-R | 7/1/2025 | $35.00 |
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.