Acorn Communicator
 | |
| Chris Whytehead's Italian-market Communicator (photo: Chris Whytehead, CC BY-SA 3.0) | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers |
| Type | Business communications terminal |
| Released | 1985[1] |
| CPU | GTE G65SC816P-2 (65816) at 2 MHz[2] |
| Memory | 128 KB or 512 KB DRAM, plus 32 KB of screen DRAM and up to 32 KB of battery-backed CMOS RAM[3] |
| Storage | None; files on an Econet file server |
| Display | RGB and composite video (6-pin DIN); BBC screen modes 0 to 6; optional LCD |
| Sound | — |
| ROM | Four 128 KB ROM sockets[4] |
| Power | External 21 V AC transformer (see Power) |
| OS / Firmware | Acorn MOS for the 65816 with menu-driven applications |
| Model no. | AFB05; AFB11 (512 KB, Italian); main board 0152,057 |
The Acorn Communicator is a desktop communications terminal that Acorn built for business customers to rebadge and resell. It has a 16-bit 65816 processor, the Electron's video ULA, a built-in auto-dial and auto-answer modem, Econet networking, serial and parallel ports, and ROM software including View, ViewSheet, Prestel and videotex, and terminal emulation. It has no disc drive; files are kept on an Econet file server such as the Acorn FileStore.[3][5]
History
[edit | edit source]The machine was first mentioned in late 1984 as the C30 and shown at the Compec show in November 1985. Acorn sold it only to companies that would customise and resell it, not through dealers.[1][6] Wikipedia reports orders in late 1986 for about 1,400 units for Pickfords Travel's shops and 500 for Thorn EMI Business Communications. Chris Whytehead records a Pickfords field change order, and that remaining stock was sold off at £34 each in 2000.[1][2] Acorn abandoned it when it closed the custom systems division in 1987.[1]
Practical Computing's January 1986 preview expected an end-user price of £1,000 to £1,500 depending on configuration.[4] Wikipedia says the Master Compact used a very similar case; Chris Whytehead compared the two and found different plastics, ports and keyboard layout.[1][2]
Hardware
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The 65816 runs at 2 MHz and addresses 16 MB in 64 KB banks. Screen memory is a separate 32 KB of DRAM driven by the Electron-derived ULA, which provides BBC modes 0 to 6; a monochrome mode 7 for Prestel is emulated in software, and a teletext daughterboard adds full-colour teletext.[3][4] Chris Whytehead's machine has a Mietec gate array with Acorn part number 0252,602 where a Ferranti ULA might be expected.[2] The I/O uses one 6522 VIA, and Wikipedia lists an AM2910PC modem chip and an SCN2641 UART from surviving units.[4][1]
| Label | Connector and use |
|---|---|
| POWER INPUT | Jack socket for the supplied mains transformer; labelled 19 V AC 50 Hz 20 W |
| DISPLAY OUTPUT | 6-pin DIN, TTL RGB or composite video (monochrome) |
| ECONET | Needs an Econet module fitted inside, the same module as the BBC Master's[2] |
| PRINTER OUTPUT | 26-way IDC header, Centronics |
| SERIAL I/O | RS423 on a 6-way telephone-style socket |
| TELEPHONE LINE INPUT | Flying lead to the telephone socket; ringer equivalence number 1.5 |
| VOLUME | Loudspeaker volume, set with a flat screwdriver |
The expansion connector is on the right-hand side of the case.[5]
Power
[edit | edit source]The Communicator has no power switch; it was designed to stay on and dial out at set times.[1] Acorn's user guide rates the supplied transformer at 240 V AC 50 Hz, 45 W in and 21 V AC at 1.6 A out, with a 3 A plug fuse, while the label on the power input socket reads 19 V AC 50 Hz 20 W.[5] Practical Computing describes a switching regulator on the main board fed from the 21 V AC input.[4] Chris Whytehead runs his from an Acorn Electron Plus 3 adaptor, which is also a 21 V AC unit.[2][7]
The clock and the configuration in CMOS RAM are kept by an internal rechargeable battery charged while the mains is on. Acorn notes that if the machine is left unused for some months the battery discharges and the Communicator may need configuring again.[5] The cell is visible as a white button on the main board in Chris Whytehead's photograph. Inspect it for leakage whenever the case is open; see Battery Explosion, Capacitor or Corrosion Damage.
Repair notes
[edit | edit source]Chris Whytehead's set of Communicator manuals includes two technical reference manuals, but only the user manuals have been scanned; the user guide itself says there are no user-serviceable parts.[2][5] His board has a small repair made with a red wire on the underside.[2] Points to check:
- Check the transformer's AC output first. The input is 19 to 21 V AC depending on the document, and the supply components on the board include electrolytic capacitors near the power socket.[5][2]
- A machine that has lost its settings after months unused may only need reconfiguring once the battery has recharged.[5]
- Garbled characters in terminal use mean wrong data bits, stop bits or parity, or a noisy line; missing text means the receive buffer is overflowing and handshaking or a larger buffer is needed.[5]
- Econet use needs an Econet module fitted to the board.[2]
Documentation
[edit | edit source]- Acorn Communicator User Guide (0452,001 issue 3, 1986).[5]
- The FileStore manager's guide written for Communicator networks is on Chris's Acorns, and the FileStore Service Manual lists the Communicator versions of the E01 and E20.[2][8]
Gallery
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Rear panel: display, Econet, printer, serial, power input and volume, with the modem lead at the right
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 "Acorn Communicator", Wikipedia (retrieved 2026-10-02). C30 name in late 1984; preview pricing; orders reported in late 1986 (500 units for Thorn EMI Business Communications, about 1,400 for Pickfords Travel); no power switch, as an always-on device; FileStore E01 and E20 versions for the Communicator; observed hardware (G65SC816, ULA, 512 KB DRAM, 32 KB static RAM, 6522 VIA, AM2910PC modem, SCN2641 UART, SAA5240 teletext decoder); monochrome first, then a colour daughterboard; the Spectar II briefcase version; abandoned when Acorn closed its custom systems division; similar case used for the Master Compact.
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 Whytehead, Chris. "Communicator", Chris's Acorns, The Centre for Computing History (retrieved 2026-10-02). GTE G65SC816P-2 at 2 MHz; 512K RAM, 32K CMOS, 256K ROM; Mietec IC with Acorn part number 0252,602 in place of a Ferranti ULA; Econet needs a standard Econet module as used on the BBC Master; BABT-approved modem (300 and 1200/75 baud); product codes AFB05 and AFB11 (512K Italian); serial 25-AFB11-1000029; main board 0152,057 issue 1; runs from an Electron Plus 3 mains adaptor; start-up message "Acorn Communicator 576K"; MOS 3.00 dated 1988 on his Italian unit; red wire repair on the underside of the board; Pickfords FCO; remaining stock sold at £34 in 2000; the Master Compact case is not the same.
- ↑ 3.0 3.1 3.2 van Someren, Alex. "Business: future of the Communicator", Acorn User, June 1986. Chris's Acorns copy (retrieved 2026-10-02). Designed for value-added retailers to rebadge (minimum order 500), no plans to sell it directly; 90-key keyboard; Electron-style expansion connector on the right; RGB, Econet, printer and LCD sockets; modem at 75, 300 and 1200 bit/s with pulse and tone dialling; 128 KB or 512 KB DRAM from 64K or 256K chips; separate 32 KB screen DRAM; up to 32 KB battery-backed CMOS RAM; four 128 KB ROM sockets; the Electron ULA ("Aberdeen") for modes 0 to 6; 65816 at 2 MHz.
- ↑ 4.0 4.1 4.2 4.3 4.4 Cullis, Roger. "Acorn Communicator office work station", Practical Computing, January 1986. Chris's Acorns copy (retrieved 2026-10-02). 65816; 128K or 512K DRAM, 32K battery-backed CMOS RAM, four 128K ROMs; RS-423 on a British Telecom jack socket at up to 19.2 kbaud; Centronics; expansion socket with 24 address lines; four-layer board; "a switching power supply derives d.c. voltages from the 21V a.c. input"; a single 6522 VIA; the modem fills the left side of the board; a large ULA for video, keyboard and sound; the twin 3.5-inch Econet file server unit; likely end-user price £1,000 to £1,500; available to OEMs only.
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 Acorn Computers, Acorn Communicator User Guide, part no. 0452,001, issue 3, first published October 1986. Hosted on this wiki: File:Acorn Communicator User Guide.pdf. Power supply rating, plug fuse and safety notes on the inside cover; switching on p. 1.1; battery-backed configuration in the configuration chapter; appendix A installation and connectors pp. A.1 to A.6; appendix B terminal emulation errors p. B.1.
- ↑ "Communicator's wide appeal", Acorn User, December 1985, p. 11. Chris's Acorns copy (retrieved 2026-10-02). First public appearance due at Compec in November; supplied direct to OEMs; 43 × 22 cm footprint; 65SC816 with a multitasking operating system in one of four 128K ROM sockets; memory 128K to 512K; battery-backed memory; disc storage in a separate twin 3.5-inch unit that can act as an Econet file server.
- ↑ "Acorn Electron", Wikipedia (retrieved 2026-10-02), section "Acorn Plus 3": the Plus 3 adaptor, part 0865,010, 21 V AC 1.75 A.
- ↑ Acorn Computers, FileStore Service Manual, part no. 0482,001, issue 1, 1989, pp. 5 and 28: E01 Communicator version 0354,000 and E20 Communicator version 0354,005. Hosted on this wiki: Acorn FileStore Documentation.