Acorn Archimedes A410
 | |
| Archimedes 400/1-series machine running RISC OS 3 | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers Ltd |
| Type | Personal computer (three-box desktop) |
| Released | A410 announced June 1987; A410/1 1989 |
| Intro price | A410 £1,399 ex VAT (1987 list); A410/1 £1,199 ex VAT |
| CPU | ARM2 at 4/8 MHz (24 MHz system clock) |
| Memory | 1 MB RAM, upgradeable to 2 MB or 4 MB |
| Storage | 3.5" floppy drive; on-board ST506 hard disc interface, no drive fitted |
| Display | — |
| Sound | 8 channels, stereo (VIDC1a) |
| OS / Firmware | A410/1: RISC OS 2.00 |
| Model no. | AKB26 (A410), AKB40 (A410/1) |
The Acorn Archimedes A410 was announced with the 400 series in 1987 but probably never sold. The A410/1 of 1989 is the 1 MB, floppy-only member of the 400/1 range, and it was sold.
The original A410 (1987)
[edit | edit source]The A410 is in Acorn's retail price list as product code AKB26, at £1,399 ex VAT with no monitor, £1,449 with a mono monitor and £1,599 with a colour monitor.[1]
Chris Whytehead doubts it was ever sold. Acorn's June 1987 announcement listed the 410 and 440; the July 1987 price list gave the A410's availability as the first quarter of 1988 and the January 1988 list as the second quarter; and the January 1988 Archimedes 440 leaflet does not mention the 410. He has never seen one, and reports hearing that all 400-series production went to the A440.[2]
The A410/1 (1989)
[edit | edit source]The 400/1 range replaced the 400 series in 1989. Chris Whytehead gives May 1989 for the launch, and names the MEMC1a memory controller as the main change.[3] Acorn's service manual for the range was first published in July 1989.[4]
| Model | Product code | RAM | Hard disc | Price ex VAT |
|---|---|---|---|---|
| A410/1 | AKB40 | 1 MB | none | £1,199 |
| A420/1 | AKB42 | 2 MB | 20 MB ST506 | £1,699 |
| A440/1 | AKB44 | 4 MB | 50 MB ST506 | £2,499 |
Product codes, RAM and drives from Chris's Acorns and Acorn's service manual;[3][4] prices from 4corn.[5]
Main board
[edit | edit source]All three 400/1 models use the Acorn Universal Board, part 0283,000; issues 2 and 3 are documented.[3] Acorn gives the processor as a 4/8 MHz ARM2 with a 24 MHz system clock and a 96 MHz master oscillator, and system performance as "typically 4 MIPS".[4]
| Device | Position |
|---|---|
| ARM2 | IC32 |
| MEMC1a | IC34 |
| IOC | IC22 |
| VIDC | IC8 |
| RISC OS ROMs | IC16, IC17, IC18, IC19 |
| HD63463 hard disc controller | IC65 |
| PCF8583 clock and NVM | IC29 |
Every 400/1 board has the ST506 hard disc interface, built round the Hitachi HD63463, including the A410/1, which has no drive.[4] ROM is 1 MB as standard in four 32-pin sockets, which take up to four 512K × 8 devices (2 MB).[4]
Memory
[edit | edit source]Memory is 1, 2 or 4 MB on one MEMC, and Acorn says there is no 3 MB option and no more than 4 MB. The AKA52 kit adds 1 MB: one kit takes an A410/1 to 2 MB and three take it to 4 MB; two take an A420/1 to 4 MB. Going from 1 to 2 MB, the new ICs interleave with the soldered ones; from 2 to 4 MB they go in the upper row of empty sockets. Links LK14 and LK15 set the memory size: both at B for 1 MB, LK14 at A and LK15 at B for 2 MB, both at A for 4 MB. Acorn made this an approved-service-centre upgrade.[4] A Simtec 4–8 MB upgrade later took one documented A410/1 to 8 MB.[6]
Expansion
[edit | edit source]A four-slot backplane, part 0283,040, is fitted as standard on a 96-way DIN 41612 connector. Three of its slots are 64-way connectors for any non-coprocessor card; the fourth is a full 96-way connector that also takes a coprocessor card.[4][3] With an Econet module fitted, only a half-width card or one shaped to clear the module (such as the I/O card) fits in the lower position.[4]
Ports
[edit | edit source]Chris Whytehead's A410/1 has, from the left: SYNC and MONO (together for a high-resolution mono monitor, or MONO alone for a standard mono monitor), analogue RGB, serial, headphones (32 Ω), parallel printer, and Econet, not fitted.[3] Acorn's specification gives the high-resolution mono output as two BNC sockets, video and sync.[4] The 400/1 serial port is based on RS232, and the RS423 driver patch (version 1.24) used with the 440 is no longer needed.[4]
Power and batteries
[edit | edit source]The power supply connects to the main board on four tags: PL11 +12 V (yellow), PL5 0 V (black), PL6 +5 V (red) and PL7 −5 V (mauve). These differ from the 300 series.[4] Mains input is 198–264 V AC, 47–63 Hz, 70 VA, and the rear outlet is unswitched, rated 3 A continuous.[4]
The real-time clock and 240 bytes of configuration RAM are kept by two LR06 (AA) 1.5 V manganese alkaline cells, which Acorn specified replacing once a year. They connect to PL10.[4] With the power off, IC29 pin 8 should read about 2.8 V; if not, check PL10, D16 and the cells, each above 1.4 V.[4] Retro-Kit found leak damage on the holder of an A410/1 bought in 2013 and rewired it.[6] See Battery Explosion, Capacitor or Corrosion Damage and Battery Refurbishment.
Capacitors
[edit | edit source]Acorn's parts list for the 400/1 main board gives these electrolytic and tantalum capacitors:[4]
| Designators | Value and type |
|---|---|
| C1, C3, C25, C48, C70, B1–B10 | 10 µF 10 V 20 % tantalum |
| C65–C69 | 47 µF 10 V axial electrolytic |
| C28, C31, C32 | 16 V radial electrolytic, printed "471J" |
| C47, C72, C73, C76, C77 | 220 µF 16 V radial electrolytic |
| C51 | 470 µF 10 V radial electrolytic |
| C27, C49 | 10 µF 16 V radial electrolytic |
| C53, C74, C75 | 100 µF 25 V radial electrolytic |
The rest are ceramic, polyester and the A1–A53 (33/47 nF) and K1–K32 (100 nF) decouplers. The value for C28, C31 and C32 is printed as "471J"; read it from the part on the board.[4]
Fault finding
[edit | edit source]Acorn's component-level checks for the 400/1 board include:[4]
- No video: +5 V on both ends of L9 (if open, check C1 for a short); about 3.5 V on IC8 pin 43 (else R73, D13, C27); 24 MHz on IC8 pin 19 through PL4a and its shunt.
- Dead system: change ARM IC32, MEMC IC34, IOC IC22 and VIDC IC8 in turn; check the RAS signal on pin 9 of every DRAM and the LK14/LK15 memory-size links.
- No sound: +5 V on both ends of L10 (if open, check C48); −5 V on IC11 pin 11; about 3 V on IC8 pin 12; about 1.5 V peak to peak at Q12 and Q14.
- Clock or settings lost: 2.8 V on IC29 pin 8, as above; crystal X3; clock signal at TP2.
Acorn's test ROMs replace the RISC OS ROMs at IC16–IC19 for a machine that fails to start, and run a memory test and a repetitive-reset test.[4]
Upgrades
[edit | edit source]On one documented A410/1, replacing a Watford Electronics 25 MHz ARM3 with an IFEL 36 MHz ARM3 raised the measured figure from about 12.72 to 17.44 MIPS.[6] On Chris Whytehead's A410/1s, an ARM2 machine gives 5,962 Dhrystones per second and an ARM3 machine 17,596.[3]
Maintenance and repair
[edit | edit source]- Guides for the 400/1 range: Acorn Archimedes 400/1 Series Maintenance Guide, Acorn Archimedes 400/1 Series Troubleshooting Guide and Acorn Archimedes 400/1 Series Capacitor Guide.
- Remove the AA cells and check the holder, its leads and the board beneath.
- Measure the rails at PL11, PL6 and PL7 against 0 V at PL5.
- Acorn's functional tests and component-level procedures are in the Acorn A400-1 and R140 Service Manual.
- Hard discs: Hard Drive Maintenance and Repair. Floppy drive: Floppy Drive Repair; Chris Whytehead's machines have Citizen OSDC-65A and OSDC-65C drives.[3]
See also
[edit | edit source]- Acorn Archimedes A420
- Acorn Archimedes A440
- Acorn Archimedes A540
- Acorn A400-1 and R140 Service Manual
References
[edit | edit source]- ↑ Acorn Computers Limited, High Performance Computer Systems Retail Price List and Pricing sheet, undated (1987). Hosted on this wiki: Acorn Archimedes Retail Price List 1987.
- ↑ Whytehead, Chris. "Acorn Archimedes A400 Series", Chris's Acorns, archived by The Centre for Computing History.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Whytehead, Chris. "Acorn Archimedes A400/1 Series", Chris's Acorns, archived by The Centre for Computing History. Product codes, launch, Acorn Universal Board 0283,000 issues 2 and 3, backplane 0283,040, HD63463P8, rear panel, documented machines and benchmark figures.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 Acorn Computers Limited, 400/1 & R140 Service Manual, part number 0483,075, issue 1, July 1989. Technical specification pp. 7–11; system description pp. 13–16; disassembly pp. 17–20; fault finding pp. 21–41; main PCB repair pp. 43–48; parts list pp. 51–64; Technical Service Bulletin 2/89 (RAM upgrade, part 0483,052, June 1989). Hosted on this wiki: Acorn A400-1 and R140 Service Manual.
- ↑ "The Acorn Archimedes", 4corn Computers (retrieved 2026-10-01): 1989 prices ex VAT of the A410/1, A420/1 and A440/1.
- ↑ 6.0 6.1 6.2 "Acorn Archimedes A410/1 with 8MB RAM", Retro-Kit (retrieved 2026-10-01). One machine: Simtec 4–8 MB upgrade, IFEL 36 MHz ARM3 replacing a Watford 25 MHz ARM3 (about 12.72 to 17.44 MIPS), battery holder leak damage cleaned and rewired.