TRS-80 Model 16
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| A Model 16 in a museum display; the keyboard has Danish characters (photo: Marcin Wichary, CC BY 2.0) | |
| Specifications | |
|---|---|
| Manufacturer | Tandy Corporation, sold by Radio Shack |
| Type | Business computer |
| Released | 1982 |
| Intro price | US$4,999 |
| CPU | Motorola MC68000 (6 MHz) and Zilog Z80A |
| Memory | 64 KB (Z80); 128 KB or 256 KB (68000) |
| Storage | One or two Tandon Thinline 8-inch floppy drives; optional hard disk |
| Display | Built-in 12-inch green monochrome monitor; 80 x 24 or 40 x 24 text |
| Sound | — |
| OS / Firmware | TRSDOS-16; Xenix; Model II operating systems |
| Predecessor | TRS-80 Model II |
| Successor | TRS-80 Model 16B |
| Model no. | 26-6001, 26-6002 |
The TRS-80 Model 16 is a Radio Shack business computer that adds a Motorola 68000 processor to the design of the TRS-80 Model II. It runs Model II software on its Z80, which also handles input and output when 68000 programs are running.[1][2] It was followed by the TRS-80 Model 16B and the Tandy 6000.[3]
History
[edit | edit source]Reed dates the Model 16's introduction to January 1982; Wikipedia gives February 1982. It ran Model II software, and Radio Shack sold a Model II to Model 16 Upgrade Kit (catalogue 26-6010) for $1,499.[1][3] At $4,999 the Model 16 sold poorly at first: by June 1982 Tandy had shipped 2,000 to its stores, most still unsold, and there were no TRSDOS-16 applications five months after launch. In early 1983 Tandy adopted Microsoft's Xenix for the machine and gave it free to existing owners; by mid-1983 an estimated 5,000 of 30,000 Model 16s ran Xenix, mostly as multi-user systems with terminals.[3] The Model 16B, with 256 KB, followed in July 1983.[3]
Hardware
[edit | edit source]The Model 16 is a dual-processor system. The Z80A side has its own CPU, floppy controller, memory and video boards and handles input and output; the 68000 side, on its own CPU and memory boards, runs the high-level language and user programs.[2]
| Board | Tandy part no. | Main parts and functions |
|---|---|---|
| Z80 CPU board | 8898020 | Z80A CPU, DMA, CTC and SIO; two RS-232 ports; 2 KB boot ROM, switched out after start-up |
| Floppy disk controller and printer interface | 8898019 | Z80 PIO, WD1791, WD1691, WD2143; internal and external drive interfaces; write precompensation adjustable from 0 to 350 ns; parallel printer port |
| 64 KB memory board | 8893498 | 4116 dynamic RAMs; jumper-selected memory page |
| Video and keyboard interface | 8898018 | MC6845 CRT controller and 2114 static RAM; 80 or 40 characters by 24 lines |
| MC68000 CPU board | 8898000 | MC68000 and AM9519A interrupt controller; up to 7 MB addressable; eight levels of vectored interrupt |
| 128K/256K memory board | 8898001 | MCM6665 64K x 1 dynamic RAMs; optional parity; can be mapped on any 256 KB boundary |
Sources: specifications and mechanical parts list.[2][4] The boards plug into an 8-slot motherboard. Options include a hard disk interface for one to four drives, a 640 x 240 high-resolution graphics board, an ARCNET network board and the 128K/256K memory board.[2]
Display, drives and power
[edit | edit source]- The 12-inch monitor has the specification of the Model II monitor with the bandwidth raised to 22 MHz, giving about 900 lines of resolution at the centre and 750 at the corners, on a green phosphor tube.[2]
- One or two Tandon Thinline 8-inch drives are built in; they take single- or double-sided disks at single or double density.[2]
- The power supply must deliver +5 V at 13.36 A, +12 V at 2.5 A, −12 V at 200 mA and +24 V at 1.7 A. The parts list gives it as a 13 A supply, Tandy 8790040, where the Model II has the Astec AA11080.[2][4]
The Model 16's Z80 boards carry different Tandy part numbers from those listed for the Model II (see the board table on the TRS-80 Model II page), so the Model II parts lists cannot be assumed to apply.[4]
Software
[edit | edit source]TRSDOS-16 ran as an extension of the Model II's TRSDOS, loading 68000 code through a shared memory window. Xenix, based on UNIX System III, supported up to three users, and Tandy sold multi-user word processing, spreadsheet, database and accounting software for it.[3]
Known faults
[edit | edit source]- The trs-80.com repair notes warn that the bleeder resistor in the CRT anode cap can fail open, leaving the tube charged after switch-off; the writer's own Model 16 had this fault.[5]
Documentation
[edit | edit source]- Radio Shack TRS-80 Model 16 Service Manual: the 68000 side, with troubleshooting charts and parts lists
- Radio Shack TRS-80 Model II Technical Reference Manual: referred to by the Model 16 manual for the Z80 side
Related pages
[edit | edit source]- TRS-80 Model 16 General Maintenance
- TRS-80 Model 16 Troubleshooting Guide
- TRS-80 Model 16 Capacitor Replacement Guide
- TRS-80 Model II
- TRS-80 Model 12
- TRS-80 Model 16B
- TRS-80 Model 6000
References
[edit | edit source]- ↑ 1.0 1.1 Matthew Reed, "The TRS-80 Model II", TRS-80.org (retrieved 2026-10-21). Section "The Model 16 and Model 12".
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Radio Shack, TRS-80 Model 16 Service Manual, catalogue numbers 26-6001/2, 1982, hosted as File:Radio Shack TRS-80 Model 16 Service Manual (26-6001, 26-6002, 1982).pdf. Introduction, p. 5, and Section 1, "Technical Specifications", pp. 7-10.
- ↑ 3.0 3.1 3.2 3.3 3.4 "TRS-80 Model II", Wikipedia (retrieved 2026-10-21). Sections "Model 16" and "Model 16B and Tandy 6000".
- ↑ 4.0 4.1 4.2 TRS-80 Model 16 Service Manual (1982), mechanical parts list, pp. 70-73.
- ↑ Ira Goldklang, "TRS-80 Troubleshooting Guide and Repair Q&A", Ira Goldklang's TRS-80 Revived Site (retrieved 2026-10-21). "All Models" section, "CRTs".