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


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


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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