Acorn Archimedes A310
 | |
| Archimedes 300-series system. The A305 and A310 are physically identical; only the DRAM fitted differs. | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers Ltd |
| Type | Personal computer (three-box desktop) |
| Released | June 1987 |
| Intro price | £875 ex VAT (base), £1,075 ex VAT with colour monitor |
| CPU | ARM2 at 4/8 MHz (24 MHz master oscillator) |
| Memory | 1 MB RAM (32 × 4464 DRAM) |
| Storage | 3.5" floppy drive, 1 MB unformatted (800 KB ADFS) |
| Display | Analogue RGB and mono composite; up to 640×256 in 256 colours, 640×512 on a multisync |
| Sound | 8 channels, stereo (VIDC1a) |
| Dimensions | 362 mm wide × 406 mm deep × 97 mm high (main unit, excluding feet) |
| OS / Firmware | Arthur 0.30, then Arthur 1.20; RISC OS 2 by ROM swap |
| Predecessor | BBC Master series |
| Successor | Acorn Archimedes A3000 |
| Model no. | AKB15 |
The Acorn Archimedes A310 was launched in June 1987 with the A305. Both use the 276,000 main board; the A310 has 1 MB of DRAM and the A305 0.5 MB.[1]
The chip set, screen modes, expansion, backup batteries, power rails, Acorn's field changes, the capacitor list and the component-level fault checks are shared with the A305 and are given on the Acorn Archimedes A305 page. The sections below cover what differs or matters most on an A310.
Prices
[edit | edit source]From Acorn's retail price list:[2]
| Product code | Configuration | RRP ex VAT | RRP inc VAT |
|---|---|---|---|
| AKB15 | A310, no monitor | £875.00 | £1,004.00 |
| AKB15/AKF01 | A310 with mono monitor | £925.00 | £1,061.50 |
| AKB15/AKF11 | A310 with colour monitor | £1,075.00 | £1,234.00 |
£999 ex VAT is the price of an A305 with a colour monitor; the A310 with a colour monitor was £1,075.[2] The A310M Archimedes Music Workstation was sold as AKB30.[1]
Processor and memory
[edit | edit source]The ARM2 has a 32-bit data bus and a 26-bit address bus and runs at 4 or 8 MHz from a 24 MHz master oscillator. Acorn quotes system performance as "typically 4 MIPS".[3]
The A310 has thirty-two 4464 DRAMs (64K × 4, 120 ns), giving 1 MB, which is the most the board takes as Acorn built it.[3] Third-party boards took 300-series machines to 4 MB. Of Chris Whytehead's three restored A310s, the 1 MB machine has the original MEMC1, and the two with IFEL 4 MB boards have MEMC1a.[1]
ROM is 512 KB in four 32-pin sockets, which take at most four 128K × 8 devices.[3]
Operating system
[edit | edit source]Chris Whytehead's A310, bought in December 1987, came with Arthur 0.30; Acorn released the Arthur 1.20 upgrade shortly afterwards, and its ROMs are dated 25 September 1987. Acorn's Arthur ROM fitting instructions say that Arthur 1.10 and 1.20 are the same.[1]
The Arthur 1.20 desktop was written in BASIC and had a palette selector, calculator, notepad, clock, calendar and diary.[1] RISC OS 2.00 (ROMs dated 5 October 1988) replaced it, and Chris Whytehead upgraded his A310 to it by changing the ROMs. His third A310 runs RISC OS 3.10 from an IFEL ROM carrier board, since the RISC OS 3 set does not fit the board's four ROM sockets.[1]
Expansion
[edit | edit source]The A310 has no expansion slots as shipped. The Acorn AKA01 backplane (part 0176,040) adds two podule positions; Chris Whytehead's third A310 has an IFEL four-slot backplane.[1][3] Total backplane draw must not exceed 20 W, and coprocessor podules are not supported.[3]
The 300-series board has no hard disc controller; the empty area on the middle right of the board is where one would sit. A hard disc on an A310 needs the AKD52 hard disc podule or a third-party podule.[1][3] The A440 has its controller on the main board.
Decoupling capacitors C37, C38 and C39
[edit | edit source]Acorn fitted three 100 µF 16 V 20 % tantalum capacitors, part 0611,101, at C37, C38 and C39.[4] The circuit diagram places C37 across +12 V (PL5), C38 across +5 V (PL7) and C39 across −5 V (PL8).[3] C37 therefore runs at 12 V on a 16 V rating.
C37 failing short is a documented fault. In a 2014 stardot thread, an A305 that showed no sign of life with the +12 V lead connected, and lit up with it removed, had a shorted C37; removing the capacitor brought the machine back, and removal is described there as a temporary fix until a new part is fitted. A tantalum that has failed short can look undamaged.[5]
To check: with the power off, measure the resistance across C37 (PL5 to PL6). With the power on, measure +12 V at PL5. If +12 V collapses with the main board connected and recovers with PL5 disconnected, remove C37. A 100 µF part rated 25 V gives more margin than Acorn's 16 V.
The rest of the capacitor list is on the A305 page.
Measured performance
[edit | edit source]Chris Whytehead's A310s are the documented measurements on this board:[1]
| Machine | CPU | Memory controller | OS | ARMSi v4.0 MIPS | SICK Dhrystone/s | kWhetstone/s |
|---|---|---|---|---|---|---|
| A310 (2) | ARM2 8 MHz | MEMC1a | RISC OS 2.00 | 4.80 | 4,797 | – |
| A310 (3) | CJE Micros ARM3 25 MHz | MEMC1a | RISC OS 3.10 | 12.75 | 17,326 | 213 |
Acorn's own figure is "typically 4 MIPS".[3]
The MEMC1a
[edit | edit source]Later 300-series machines and all A400/1 machines use the MEMC1a. Chris Whytehead describes it as giving "a slight performance improvement" over the older systems.[6] On ARMSi v4.0 his ARM2 machines measure 4.80 MIPS for the MEMC1a A310, 4.82 for a MEMC1a A3000 and 4.56 for a MEMC1 A440.[1][7][8] The A540 and A5000 run their MEMC1a at a 12 MHz memory clock; the A310's memory clock is 8 MHz.[9][10]
Maintenance and repair
[edit | edit source]- Remove the two AA alkaline cells from the holder on the base metalwork. Acorn specified replacing them once a year; cells left in for decades leak. See Battery Explosion, Capacitor or Corrosion Damage.
- Check C37, as above.
- Measure the supply rails at PL5–PL8. Acorn says a clicking PSU means a short between outputs or a faulty supply.[3]
- Check the ROM links LK2, LK6 and LK12 after any ROM change.[3]
- Floppy drive: see Floppy Drive Repair. Tools: see Recommended Tools.
Acorn's production faults and field change orders for the board (speaker hum, RGB levels, video noise, the Q9/Q11 audio transistors and the issue 1 serial links) are listed on the A305 page.[3]
Documentation
[edit | edit source]- Archimedes 300 Series Service Manual
- Archimedes 300 Series Service Manual Component Level Supplement
- Acorn Archimedes Retail Price List 1987
See also
[edit | edit source]- Acorn Archimedes A305, the same board with half the memory
- Acorn Archimedes A440
- Acorn Archimedes A3000
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 Whytehead, Chris. "Acorn Archimedes A300 Series", Chris's Acorns, archived by The Centre for Computing History. Launch date, product codes AKB15 and AKB30, motherboard 276,000 Issue 2, Arthur 0.30 and 1.20, three restored A310s with their configurations and benchmark figures.
- ↑ 2.0 2.1 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.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Acorn Computers Limited, Archimedes 300 Series Module Level Service Manual, part number 0476,140, issue 1, April 1988. Section 1.2 technical specification (pp. 5–9); section 2 system description (pp. 11–13); section 5 connectors and test points (pp. 19–24); section 6 fault finding (pp. 25–29); appendix 7.2 production and field changes (pp. 32–34); circuit diagram sheet 2 (p. 81). Hosted on this wiki: Archimedes 300 Series Service Manual.
- ↑ Acorn Computers Limited, Archimedes 300 Series Service Manual Component Level Supplement, part number 0476,145, issue 1, October 1988. Section 5.1 parts lists. Hosted on this wiki: Archimedes 300 Series Service Manual Component Level Supplement.
- ↑ "A305 12v line issues", stardot.org.uk forums, February 2014. Machine dead with +12 V connected; C37 found shorted and removed; note that a shorted tantalum can look perfect when the supply limits the fault current.
- ↑ Whytehead, Chris. "Acorn Archimedes A400/1 Series", Chris's Acorns, archived by The Centre for Computing History.
- ↑ Whytehead, Chris. "BBC A3000", Chris's Acorns, archived by The Centre for Computing History.
- ↑ Whytehead, Chris. "Acorn Archimedes A400 Series", Chris's Acorns, archived by The Centre for Computing History.
- ↑ Whytehead, Chris. "Acorn Archimedes A540", Chris's Acorns, archived by The Centre for Computing History.
- ↑ Whytehead, Chris. "Acorn A5000", Chris's Acorns, archived by The Centre for Computing History.