TRS-80 Model 16B
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| The Built-in Hard Disk System console and keyboard, as pictured in Tandy's 1983 Model 16B manual | |
| Specifications | |
|---|---|
| Manufacturer | Tandy Corporation, sold by Radio Shack |
| Type | Multi-user business computer |
| Released | July 1983 |
| CPU | Motorola MC68000 and Zilog Z80A |
| Memory | 256 KB at launch for the 68000; 64 KB for the Z80A |
| Storage | 8-inch double-sided floppy drive; 15 MB built-in hard disk on the Built-in Hard Disk System |
| Display | Built-in monochrome monitor; 80 x 24 or 40 x 24 text |
| Sound | — |
| OS / Firmware | TRS-XENIX; TRSDOS-II |
| Predecessor | TRS-80 Model 16 |
| Successor | Tandy 6000 |
The TRS-80 Model 16B is the 1983 update of Radio Shack's TRS-80 Model 16, a business computer that pairs a Motorola 68000 with the Z80A design of the TRS-80 Model II. It was widely used as a Xenix multi-user system, and was followed in 1985 by the Tandy 6000.[1][2]
History
[edit | edit source]Tandy introduced the Model 16B, with 256 KB, in July 1983. Wikipedia, citing InfoWorld, calls it the most popular Unix computer of 1984, with almost 40,000 sold.[1] BYTE reviewed it in January 1984 as "a fairly well-implemented and apparently well-supported Xenix system", and in August 1984 as "a usable multiuser microcomputer system" whose slow hard disk might limit it to two users.[1] The Tandy 6000 replaced it in 1985.[1]
Hardware
[edit | edit source]Tandy's Built-in Hard Disk System manual describes the machine as two processor systems sharing the work:[2]
| Part | Description |
|---|---|
| Input/output processor | Z80A with 64 KB of RAM and its own bus for the standard system boards; runs Model II programs unchanged in emulation mode |
| Computational processor | 68000 with its own bus supporting several bus masters; the manual gives 384 KB or 512 KB on a Model 16B |
| Video | LSI controller; green or white on black, or reversed; 80 x 24 or 40 x 24 characters; full ASCII and 32 graphics characters |
| Keyboard | Separate case with its own LSI controller; built-in coiled cord leaving the lower back; eight function keys |
| Floppy drives | One built-in 8-inch double-sided drive; up to two more in an external expansion unit |
| Hard disk | 15 MB built in (drive 4): six heads and 306 cylinders, 5 Mbit/s transfer rate, sealed head and disk chamber; one secondary external hard disk (drive 5) can be added |
| Ports | Two RS-232C serial ports on DB-25 connectors (channel A asynchronous or synchronous, channel B asynchronous); parallel printer port; floppy expansion connector; hard disk interface |
| Options | ARCNET interface; graphics board |
Sources: Appendix D and chapter 1.[2][3]
The memory figures do not agree: Wikipedia gives 256 KB for the 16B at launch, while the manual gives 384 KB or 512 KB.[1][2] Wikipedia says the 68000 was raised to 8 MHz with the Tandy 6000; no clock speed for the 16B is given in the sources used here.[1]
Service documentation
[edit | edit source]No Model 16B service manual has turned up in online archives. Tandy's 1985 service manual for the 6000 refers to one: a 6000 whose fan sits in a metal housing on the back of the access panel is to be taken apart following the Model 16B service manual.[4] The same manual's hard disk section, apparently carried over from Model 16B material, describes the built-in hard disk machine as "identical to the standard 16B (Cat. No. 26-6004)" apart from the 15 MB drive, its controller board, its power supply and cables.[5] The 6000's internal hard disk, a Tandon TM503, has the same six heads and 306 cylinders as the 16B's.[5][6]
Specifications
[edit | edit source]| Item | Value |
|---|---|
| Mains | 105-130 V AC, 60 Hz; 240 V AC, 50 Hz (Australia); 220 V AC, 50 Hz (Europe); grounded outlet |
| Current | 1.5 A typical, 2.0 A maximum |
| Restart delay | At least 15 seconds between switching off and on again |
| Operating temperature | 55-85 °F (13-29 °C) |
| Floppy data rate | 500,000 bit/s (250,000 bit/s on track 0) |
| Diskette life | 3.5 million passes per track |
Source: [2]
Software
[edit | edit source]The Built-in Hard Disk System was supplied with TRS-XENIX (three system diskettes), TRSDOS-II with BASIC, and Thinline TRSDOS 2.0b with BASIC. The hard disk is prepared either for TRS-XENIX, with the diskutil program, or for TRSDOS-II, with FORMAT.[3][6] Tandy's Xenix for the Model 16 line was based on UNIX System III.[1]
Known faults
[edit | edit source]- No fault reports specific to the 16B were found. The trs-80.com repair notes, which cover the whole range, warn that the bleeder resistor in the CRT anode cap can fail open and leave the tube charged; the writer's own Model 16 had this fault.[7]
- On a new or blank hard disk the machine stops with "BOOT ERROR HN" until drive 4 has been formatted. The boot error table is on the TRS-80 Model 16B Troubleshooting Guide.[6]
Documentation
[edit | edit source]- Radio Shack TRS-80 Model 16B Built-in Hard Disk System Manual: installation, power-up, hard disk preparation, maintenance, error tables and specifications
- Radio Shack TRS-80 Model 16 Service Manual: the 68000 boards of the original Model 16
- Tandy 6000 Service Manual: the successor's full service manual
Related pages
[edit | edit source]- TRS-80 Model 16B General Maintenance
- TRS-80 Model 16B Troubleshooting Guide
- TRS-80 Model 16B Capacitor Replacement Guide
- TRS-80 Model 16
- TRS-80 Model 6000
- TRS-80 Model II
- TRS-80 Model 12
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "TRS-80 Model II", Wikipedia (retrieved 2026-10-21). Sections "Model 16B and Tandy 6000" and "Reception".
- ↑ 2.0 2.1 2.2 2.3 2.4 Radio Shack, TRS-80 Model 16B Built-in Hard Disk System Manual, 1983, hosted as File:Radio Shack TRS-80 Model 16B Built-in Hard Disk System Manual (1983).pdf. Appendix D, "Specifications", pp. 60-63.
- ↑ 3.0 3.1 TRS-80 Model 16B Built-in Hard Disk System Manual (1983), Chapter 1, "Installing Your Built-in Hard Disk System", pp. 5-11.
- ↑ Tandy Computer Products, Service Manual, Tandy 6000/6000-HD, catalogue numbers 26-6021/2, 1985, hosted as File:Tandy 6000 Service Manual (26-6021, 26-6022, 1985).pdf. Section 3, p. 9.
- ↑ 5.0 5.1 Service Manual, Tandy 6000/6000-HD (1985), Section 7.10.1, "System Overview", p. 219.
- ↑ 6.0 6.1 6.2 TRS-80 Model 16B Built-in Hard Disk System Manual (1983), Chapter 4, p. 21, and Chapter 5, p. 23.
- ↑ 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".