Marcel Erz Brings Again the TRS-80 Mannequin I with a Excessive-Accuracy, Open-{Hardware} PCB Duplicate

Classic computing fanatic Marcel Erz is bringing again the Tandy-Radio Shack TRS-80 dwelling laptop — with a trace-for-trace reimplementation of the unique Mannequin I motherboard, launched below a permissive license.

“This venture is a trustworthy reimplementation of the mainboard of the enduring TRS-80 Mannequin I (Revision G) laptop,” Erz writes of his work. “My very own revision, the E1, is designed to copy 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 venture is on the market below the MIT license.”

Launched by Tandy in 1977 and offered by 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 dwelling laptop with 4kB of RAM, upgradeable to 48kB in 16kB steps, and was a serious hit for the corporate — changing into not solely one in all its greatest sellers however the best-selling dwelling laptop of its period, spawning a spread of suitable 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 are not the rarest issues round, authentic TRS-80 Mannequin Is are undoubtedly exhibiting 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 an extra capacitor not documented within the machine’s reference handbook, are mounted within the new design.

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. All the pieces is constructed to the unique specification, which means period-appropriate parts would be the order of the day — although in lots of instances trendy equivalents can be found, whereas different components will should be sourced from previous inventory or discarded units. A set of ordering directions can also be supplied “to get a extra trustworthy model of the board,” Erz says.

The venture’s design recordsdata can be found on the RetroStack GitHub repository below the permissive MIT license.