Trevor Flowers' Miniature TRS-80 Microcomputer Houses an Adafruit QT Py for a Working Display

Built around an Adafruit QT Py, this 1:6-scale TRS-80 Model III boasts considerably higher specifications than the original.

Maker and vintage computing enthusiast Trevor Flowers has put together an ultra-compact clone of the Tandy-Radio Shack TRS-80 microcomputer — powered by an Adafruit QT Py board running CircuitPython.

Released in 1977 by Tandy through its Radio Shack store fronts, the original TRS-80 — later rebadged to the Model I — kicked off a family of microcomputing devices which would run the gamut from all-in-one systems with floppy drives and CRT displays to the popular TRS-80 Model 100 portable. The TRS-80 Model II, released in 1980, came with the aforementioned display, up to two 180kB floppy drives, up to 48kB of RAM, and a Zilog Z80A processor running at 2MHz.

This tiny TRS-80 packs an Adafruit QT Py S3 microcontroller board, giving it specifications far in excess of full-size originals. (📹: Trevor Flowers)

Flowers' miniature recreation, though, has very different specifications. Inside the 3D-printed chassis lies an Adafruit QT Py S3 microcontroller development board, which despite its diminutive size boasts an Espressif ESP32-S3 chip with two Tensilica Xtensa LX7 cores running at up to 240MHz, 512kB of static RAM (SRAM), 2MB of pseudo-static RAM (PSRAM), and 4MB of flash storage — all upgrades on the TRS-80 by multiple orders of magnitude.

"This [miniature] is driven by this QT Py running CircuitPython or Arduino," Flowers explains. "So, there's not an accurate TRSDOS or VDOS emulator for it. On the other hand it has Wi-Fi, BLE [Bluetooth Low Energy], and more memory and pixels than the original."

The project builds on Flowers early display-only TRS-80 miniature model, which lacked electronics and instead used swappable cards to simulate a static display. "As shipped," Flowers explained of the original, which was created to a 1:6 scale, "it will show a short BASIC program." The new variant, though, can display animations — or even double as a functional Internet of Things (IoT) connected display system in a retro-themed chassis.

More information on the project is available on Flowers' Mastodon thread, while the non-functional variant is listed for sale on his Transmutable store at $42.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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