Acorn Archimedes A3010

Acorn Archimedes A3010

A3010 with an Acorn colour monitor
Specifications
Manufacturer	Acorn Computers
Type	Home computer
Released	September 1992
Intro price	£424.68 plus VAT (£499 including VAT) as the Family Solution bundle
CPU	ARM250 at 12 MHz
Memory	1 MB, expandable to 2 or 4 MB
Storage	3.5-inch floppy drive; no internal hard disc
Display	Analogue RGB (also drives a SCART TV); UHF TV modulator
Sound	Stereo; internal speaker and headphone socket
ROM	2 MB (RISC OS 3)
Power	10 W supply on the main board
Dimensions	479 × 267 × 73 mm
Weight	4.1 kg
OS / Firmware	RISC OS 3.10 or 3.11
Predecessor	Acorn Archimedes A3000
Model no.	AGB11 (1 MB), AGB15 (2 MB, Family Solution), AGB40 (2 MB), AGB50 (Action Pack)

The Acorn Archimedes A3010 is a home computer that Acorn Computers announced in August 1992 and sold from September 1992. It has the keyboard, main board, power supply and floppy drive in one case, like the A3000 it replaced, and uses the ARM250, which combines the ARM2 processor with the MEMC1a, VIDC1a and IOC functions in one chip. It was the home model of a range that also included the A3020 for schools and the A4000.

History

Acorn's launch announcement said the A3010 was designed for the home user, with a UHF TV modulator for use with a television and two ports for switched joysticks. It has a grey case and green function keys. The range started at £424.68 plus VAT (£499 including VAT) for the A3010 "Family Solution", which added the EasiWord word processor, the game Quest for Gold, an audio training tape and blank discs. The "Learning Curve" bundle paired a 2 MB A3010 with a colour monitor, Genesis applications and Acorn's PC emulator.

The machines were sold through high-street retailers including Dixons, John Lewis and Argos. A late-1993 "Action Pack" bundle with the game Zool brought the A3010 down to £399 including VAT, and in late 1994 Acorn appointed a sole distributor for the A3010 bundles, which cut the Action Pack to £299.

Chris Whytehead also documents a late batch of A3010s in beige cases with red function keys, sold by Castle Technology. According to David Holden of APDL, quoted there, these were surplus machines built for the German market and fitted by Castle with UK ROMs and A3020 keyboards.

Specifications

Acorn's feature table compares the three ARM250 machines:

A3010, A3020 and A4000 compared (Technical Reference Manual p. 1-1)

Feature	A3010	A3020	A4000
Design	Single box	Single box	Twin box
Processor	12 MHz ARM250	12 MHz ARM250	12 MHz ARM250
Base memory	1 MB	2 MB	2 MB
Expandable to	2 or 4 MB	4 MB	4 MB
Operating system	RISC OS 3, 2 MB ROM	RISC OS 3, 2 MB ROM	RISC OS 3, 2 MB ROM
Hard disc	None	Optional internal 2.5-inch IDE	Optional internal 3.5-inch IDE
Keyboard	103 keys, integral	103 keys, integral	103 keys, separate
Power supply	10 W	12.5 W	24 W
Colour TV modulator	Yes	No	No
Internal network expansion	No	Yes	Yes
Switched joystick inputs	2	No	No
Rechargeable clock battery	Yes	Yes	Yes

The Computer History Museum's example measures 479 × 73 × 267 mm and weighs 9 lb (4.1 kg). Chris Whytehead's three A3010s measured 7.17-7.22 MIPS on ARMSi 4.0.

Hardware

Main board

Acorn's Technical Reference Manual gives separate parts lists for two kinds of A3010 main board.

• Early boards carry a daughter card (Acorn's CPU module, 0194,002) with a discrete-component version of the ARM250: a 12 MHz ARM, MEMC1a, VIDC1a, IOC and an IOEB chip. Acorn's Appendix D says initial production of all three machines used this card, that the two boards are functionally the same with most components in the same positions under the same references, and that the card is clocked by 36 MHz and 24 MHz oscillators instead of the single 72 MHz oscillator used with the ARM250.
• Later boards have the ARM250 (IC13, part 0294,030) soldered to the board. Chris Whytehead records ARM250 boards numbered 0194,003 and 0195,200 and an early board numbered 0194,004.

Other main parts on the ARM250 board are two 256K × 16 DRAMs (IC21, IC22), two RISC OS ROMs (IC17, IC18), an 82C711 peripheral controller (IC24), the keyboard controller (IC2), an 8583 clock and CMOS RAM chip (IC5), a 1145 RGB encoder (IC1) and UHF modulator for the TV output, and an LM386 speaker amplifier (IC10). Most of the audio circuit is on a plug-in hybrid module (IM2, part 0194,007).

Power supply

The supply is part of the main board and cannot be removed separately. A 25 VA mains transformer (L1) has two secondary windings. The main one is rectified and smoothed to about 23 V at TP1, which an L4960 step-down switching regulator (Q2) running at about 100 kHz turns into the 5 V rail; a 78L12 (Q1) makes a regulated 12 V for the SCART interface and the audio hybrid's op-amp. The second winding is centre-tapped and gives unregulated +12 V and -12 V at TP2 and TP3, 50 mA, for the RS232 circuits. The ±12 V rails are fused, and the transformer contains a thermal fuse that is not to be bypassed; if it fails, the transformer is replaced.

Acorn's manual warns that the supply is sized for Acorn's own upgrade options, that the current limit of the switching regulator varies widely from unit to unit, and that a machine which appears to power a demanding third-party upgrade may still overheat or fail early.

Backup battery

The clock and CMOS RAM are backed by BT2, a 1.2 V 280 mAh nickel cell soldered to the board (Acorn part 0817,014, "BAT NI 1V2 280MAH VT PCB"). It sits at the top right of the board, under the floppy drive. Appendix D notes that the battery was moved between the early and ARM250 boards.

Ports

From left to right on the rear panel: parallel printer port, serial port, two joystick ports, mouse, headphones, analogue RGB monitor and the TV modulator socket. Above them is a blanking panel for a mini-podule. There is no Econet or network socket. The video socket carries +12 V on pin 12 when driving a SCART TV.

Known faults

• Battery leakage. BT2 leaks onto the top-right corner of the board and the inside of the metal shield around it. See the Acorn Archimedes A3010 Maintenance Guide.
• Upgrades and the supply. Owners on the Stardot forum have reported A3010s that start only after several attempts once a 4 MB upgrade and an IDE hard disc are fitted. Acorn's own note on the supply's limited capacity is quoted above.
• Crackling audio. On the Stardot forum, broken pins on the audio hybrid module and dirty switched contacts in the headphone socket were found to cause crackle.

Diagnosis is covered on the Acorn Archimedes A3010 Troubleshooting Guide, and the capacitor list on the Acorn Archimedes A3010 Capacitor Guide.

Documentation

• Acorn A3010, A3020 and A4000 Service Manual: Acorn's module-level service manual, part 0494,059, with fault-finding flowcharts, the power-on self-test codes, disassembly and the dealer test disc procedures.
• Acorn A3010, A3020 and A4000 Technical Reference Manual: system description, power supply, links, connectors and full parts lists for every board.
• Main PCB circuit diagram, Acorn's "Adelaide Main PCB" drawing 0194,000, which shows the early board with the CPU daughter card: sheet 1, sheet 2 and sheet 3.

Gallery

• 
  A3010 main board with the ARM250
• 
  Main PCB circuit diagram, sheet 1
• 
  Main PCB circuit diagram, sheet 2
• 
  Main PCB circuit diagram, sheet 3

Related pages

• Acorn Archimedes A3010 Maintenance Guide
• Acorn Archimedes A3010 Troubleshooting Guide
• Acorn Archimedes A3010 Capacitor Guide
• Acorn Archimedes A3020 and Acorn Archimedes A4000
• Acorn Archimedes A3000