Welcome to the Model I Replacement Expansion Interface (MIRE) Project!


The MIRE is a modern replacement for the TRS-80 Model I Expansion Interface. It connects to the expansion port on the left rear of the Model I keyboard unit. MIRE provides these features and benefits:

The AC adapter (US-style plug, UL-listed) needed to power the MIRE, and the ribbon cable assembly to attach the MIRE to the TRS-80, are both included.

Minimum system requirements: TRS-80 Model I with 16KB and Level II BASIC.

Product Pricing

Price list


February 18, 2018: MIRE is SOLD OUT and I have no immediate plans to build any more. Thanks to all those who supported the project. If there's enough continuing interest I'll eventually order a new batch of PCBs.

May 15, 2017: A very small number of MIRE units are now available for purchase.

March 9, 2017: A couple photos of "what's in the box":

March 3, 2017: The PCBs arrived on February 20. The Alpha test unit went together smoothly and worked well, so now Beta testing is underway!

January 17, 2017: The first batch of MIRE PCBs is on order! When they arrive there will be a Beta Test period before units are made available to everyone. Here's a rendering:

Yes, they're gonna be black!

Much more information to come on setting up and using the MIRE.


Setting up the MIRE

MIRE and floppy drives

32KB SRAM expansion

Heartbeat interrupt

The RS-232 port

The line printer port

Cassette audio output

Expansion port

MIRE I/O ports


Unified File Releases

SD Card Files

Programming Files

Building an enclosure

Matthew Reed's TRStools application is great for manipulating the contents of DMK files, or for creating new, blank images.


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