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


June 2023: All of the MIRE components have finally become available again. I am slowly building new MIRE units. I'm contacting (in FIFO order) those who during the hiatus expressed interest in obtaining one.

July 2022: MIRE is out of production until approximately May of 2023. Several of the key components will not be available until then.

June 2018: MIRE 1.1 PCBs are in, and are slowly being assembled and tested. The primary difference from MIRE 1.0 is that I've changed PCB suppliers, and the board now sports immersion gold for better contact and less oxidation on the card edge connectors.

I have provided them to everyone who expressed interest at the end of MIRE 1.0 production, so let me know if you want one and I'll put you on the list.

September/October 2017: MISE, M3SE, and MIRE at VCF Midwest 12 and Tandy Assembly!

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

Programming the MIRE

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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