Classic computing fanatic Marcel Erz is bringing again the Tandy-Radio Shack TRS-80 house pc — with a trace-for-trace reimplementation of the unique Mannequin I motherboard, launched below a permissive license.
“This mission is a trustworthy reimplementation of the mainboard of the enduring TRS-80 Mannequin I (Revision G) pc,” Erz writes of his work. “My very own revision, the E1, is designed to duplicate the unique system’s performance by utilizing a PCB design 1-to-1 to the unique, together with parts, interfaces, and even traces. Your entire mission is obtainable below the MIT license.”
Marcel Erz is bringing the TRS-80 microcomputer again in type, with a lovingly-cloned and fully-compatible motherboard. (📷: Marcel Erz)
Launched by Tandy in 1977 and offered by way of its Radio Shack shops, therefore the letters “TRS” in its title, the TRS-80 Mannequin I used to be a Zilog Z80-based eight-bit house pc with 4kB of RAM, upgradeable to 48kB in 16kB steps, and was a significant hit for the corporate — changing into not solely considered one of its largest sellers however the best-selling house pc of its period, spawning a spread of appropriate follow-ups together with the famously transportable TRS-80 Mannequin 100.
Whereas its best-selling nature and quite a few follow-ups imply that they don’t seem to be the rarest issues round, authentic TRS-80 Mannequin Is are undoubtedly displaying their age — which is the place Erz’ “E1” is available in. The board, designed in KiCad 7, is a trustworthy duplicate of the unique — even right down to unused vias and holes used throughout Tandy’s authentic manufacturing course of to maintain the boards in place. Different errors, together with a further capacitor not documented within the machine’s reference handbook, are fastened within the new design.
The board is designed to imitate, as carefully as attainable, the unique Tandy design (pictured). (📷: Binarysequence, CC-BY-SA 4.0)
So as to flip the PCB right into a fully-functional TRS-80 Mannequin I, you will want parts — and right here Erz’ work features a full invoice of supplies. The whole lot is constructed to the unique specification, which means period-appropriate parts would be the order of the day — although in lots of circumstances fashionable equivalents can be found, whereas different components will should be sourced from previous inventory or discarded gadgets. A set of ordering directions can also be supplied “to get a extra trustworthy model of the board,” Erz says.
The mission’s design recordsdata can be found on the RetroStack GitHub repository below the permissive MIT license.
