The MIRE Project

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

Overview

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:

32KB SRAM, expanding your system to a full 48KB. The additional RAM can be disabled for those with RAM upgrades already within the keyboard unit.
Single/double density, single/double sided floppy controller, compatible with the original doublers from Radio Shack and Percom/Aerocomp.
Emulated floppies on Secure Digital (SD). Includes a full-featured TRS-80 application for manipulating files and mounting DMK files as floppies. Floppies and files can also be controlled from a PC using an SD card reader/writer. Included SD card has bootable LDOS installed, but MIRE also works with other DOSes (NewDOS, MultiDOS, TRS-DOS, etc.)
RS-232 on a 9-pin D-SUB connector, compatible with the original Model I RS-232 expansion board from Radio Shack. Includes a 64-byte receive FIFO to help prevent overruns.
Line printer port on a DB-25 connector, compatible with the original expansion interface.
Cassette sound output on a 3.5mm jack. Includes RC filtering to improve sound quality.
Expansion port for connecting your MISE or vintage peripherals.
Heartbeat interrupt for maintaining DOS software clocks.

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

Status

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: