TRS-80 Model 12
 | |
| The TRS-80 Model II, which the Model 12 replaced (photo: Piergiovanna Grossi, CC BY-SA 4.0). No free photo of the Model 12 itself was found. | |
| Specifications | |
|---|---|
| Manufacturer | Tandy Corporation (sold through Radio Shack) |
| Type | Business computer |
| Released | 1982 |
| CPU | Zilog Z80A |
| Memory | Up to 768 KB |
| Storage | Half-height ("thinline") double-sided floppy drives |
| Display | Built-in CRT with green phosphor |
| Sound | — |
| OS / Firmware | — |
| Predecessor | TRS-80 Model II |
The TRS-80 Model 12 is the Z80 business computer that replaced the TRS-80 Model II in 1982, part of the line that also includes the Model 16, Model 16B and Tandy 6000.[1][2] Radio Shack discontinued the Model II in 1983, after the Model 12 was introduced, and sold business software for the two machines alike.[2][3]
Hardware
[edit | edit source]The Model 12 puts most of the Model II's electronics, which on the Model II were spread over several plug-in cards, onto a single main board. The video and keyboard card plugs into one slot on the main board, and an optional card cage adds six more slots. The full-height floppy drive of the Model II gives way to half-height ("thinline") double-sided drives, and the white-phosphor screen to a green one. The keyboard has eight function keys, and the serial and Centronics printer ports are grouped at the rear left. With 4164 memory chips and a revised bank-switching scheme it takes up to 768 KB of RAM. In Wikipedia's description it is essentially a Model 16B without the card cage and the Motorola 68000 boards, and it can be upgraded to a Model 16B.[1]
Radio Shack's ARCNET network board (catalogue number 26-6501) installs in an existing card slot at the rear of the Model 12; on a Model II it also needs a 16K Z-80 memory expansion board if the computer has not been used with a hard disk.[3]
Reception
[edit | edit source]80 Micro called the Model 12 "not a major innovation, but an evolutionary" step in 1982, fixing most of the Model II's faults apart from the old Z80A and the noise. InfoWorld in 1983 described it as "a refined" Model II and "a solid, well-conceived business computer", but advised a different operating system from TRSDOS.[1]
Service documentation
[edit | edit source]Ira Goldklang's TRS-80 Revived lists Tandy documents for the Model 12: a Model 12 Owner's Manual (1982, with the number 26-4004), the Model 12 and 16B Technical Bulletins 1 to 44 (1986) and a Model II/12/16/16B ROM checksum document, but its downloads only work from links on its own pages.[4]
The Model II guides describe the earlier machine, with its card cage of separate boards and its own power supply: see TRS-80 Model II General Maintenance, TRS-80 Model II Troubleshooting Guide and TRS-80 Model II Capacitor Replacement Guide. The Model 12 has a different main board and drives, so check each part against your own machine before following those procedures. Tandy's service manual for the later Tandy 6000 is hosted as File:Tandy 6000 Service Manual (26-6021, 26-6022, 1985).pdf; it covers that machine only.[5]
Related pages
[edit | edit source]- TRS-80 Model II
- TRS-80 Model II General Maintenance
- TRS-80 Model II Troubleshooting Guide
- TRS-80 Model II Capacitor Replacement Guide
- Radio Shack TRS-80 Model II Technical Reference Manual
References
[edit | edit source]- ↑ 1.0 1.1 1.2 Wikipedia, "TRS-80 Model II", revision of 19 August 2026 (retrieved 2026-10-21), sections "Model 12", "Model 16B and Tandy 6000" and "Reception": the Model 12 replacing the Model II in 1982; half-height double-sided floppy drives; most of the Model II electronics on a single main board; the video and keyboard card in one slot; the optional six-slot card cage; the green-phosphor CRT; eight function keys; the ports at the rear left; up to 768 KB of RAM with 4164 chips; the Model 12 as a Model 16B without the card cage and 68000 boards, and upgradable to one; reviews in 80 Micro (1982) and InfoWorld (1983).
- ↑ 2.0 2.1 Matthew Reed, "The TRS-80 Model II", TRS-80.org (retrieved 2026-10-21): the Model II line including the Model 16, Model 12 and Tandy 6000; the Model II discontinued in 1983 after Radio Shack introduced the Model 12 as its replacement.
- ↑ 3.0 3.1 Ira Goldklang, "Model 2/12/16/1000", TRS-80 Revived (retrieved 2026-10-21): reproduced Radio Shack catalogue text for the ARCNET board, 26-6501, and software requiring a Model II, Model 12 or Model 16.
- ↑ Ira Goldklang, hardware manuals list, page 2, TRS-80 Revived (retrieved 2026-10-21): "Model 12 Owners Manual (1982)(Tandy)[26-4004]", "Model 12 and 16B Technical Bulletins 01-44 (1986)(Tandy)" and "Model II-12-16-16B ROM Checksum v1.2 (1984)(Tandy)".
- ↑ Tandy, Service Manual: Tandy 6000/6000-HD, catalogue numbers 26-6021/2, copyright 1985, hosted as File:Tandy 6000 Service Manual (26-6021, 26-6022, 1985).pdf: the Tandy 6000 and 6000-HD, its main logic board described as "functionally equivalent and software compatible with the TRS-80 Model II" (section 7.4), and a reference to the Model 16B service manual for some units (section 3).