--- title: Acorn Computer A4 categories: - Computers types: - Portable origins: - United Kingdom years: - '1991' cpus: - ARM 3 params: name: A4 company: /companies/acorn-computer company_name: Acorn Computer specs: - label: NAME value: A4 - label: MANUFACTURER value: Acorn Computer - label: TYPE value: Portable - label: ORIGIN value: United Kingdom - label: YEAR value: '1991' - label: KEYBOARD value: 84 keys with arrow keys - label: CPU value: ARM 3 (with 4 KB of internal RAM cache) - label: SPEED value: 24 mHz (internal CPU) and 12 mHz (bus) - label: RAM value: 4MB - label: ROM value: 2 MB - label: TEXT MODES value: 'Max : 132 x 30' - label: GRAPHIC MODES value: 47 graphic modes, maximum 640 x 480 with LCD screen and up to 1152 x 896 with VGA screen - label: COLORS value: 14 shades of grey (LCD screen) - label: SOUND value: 8 voices (stereo 8 bit) - label: I/O PORTS value: VGA, Centronics, RS232 C, stereo sound, Mouse, Keyboard - label: BUILT IN MEDIA value: one 3.5'' disk-drive - label: OS value: RISC OS 3.10 - label: POWER SUPPLY value: External PSU - label: PRICE value: £1395 (2Mb floppy version) up to £1895 (4Mb HD120 version) tabs: - photos - hardware - emulators - links - docs photos: - title: ACORN A4 subtitle: '' text: The A4 used a slightly modified version of the Olivetti M15 laptop case. image: null - title: TOP VIEW subtitle: '' text: '' image: null - title: BOTH SIDES subtitle: '' text: |- On the right hand side:\ • 3.5" floppy disk drive\ • Stereo headphone jack\ • External standard AT keyboard mini-DIN socket\ • Acorn mouse mini-DIN socket\ • Serial RS232 DB9 connector On the left hand side:\ • Battery pack\ • Trap door allowing to exchange ROM and RAM chips. image: null - title: REAR CONNECTORS subtitle: '' text: |- From left to right:\ • 2nd serial port\ • External PSU connector\ • Standard VGA 15-pin video output. image: null - title: INSIDE subtitle: '' text: Note the battery pack, the slim size Epson floppy disk drive and the Conner 3.5" 60 MB hard disk drive. image: null - title: MOTHERBOARD subtitle: '' text: |- **(1)** LCD display connectors\ **(2)** VLSI Arm co-processors. They manage I/O's, video, memory, FDD & HDD.\ **(3)** Hard drive connector\ **(4)** Floppy drive connector\ **(5)** ARM 3 processor\ **(6)** RISC OS 3.10 ROMs\ **(7)** 4 MB RAM chips. image: null hardware: - title: 486 CARD subtitle: '' text: Allowed Archimedes series computers to run 32-bit PC-DOS software. It was delivered with a manual, a driver disk and PC-DOS 6.3 image: null - title: GRAPHICS ACCELERATOR subtitle: '' text: |- Graphics accelerator card (called "ColourCard") for A3000, Archimedes and A5000.\ Company : Computer Concepts\ Enhanced potential for Archimedes series including 15-bit desktop modes (i.e. 800\*600 @ 256 colours). Thanks to **Chris Syntichakis** image: null - title: CUMANA SCSI CARD subtitle: '' text: |- 16-bit SCSI-1 card\ Company: Cumana.\ There are an external port for scanners/CD-ROM etc. and 2 internal ports for SCSI and Floptical drives. Thanks to **Chris Syntichakis** image: null - title: SERIAL CARD subtitle: '' text: |- From Atomwide's site:\ High speed serial card featuring three ports, each in the shape of a standard 9-pin ‘D’ plug. Each port on the card is capable of running at up to 460,800 bits per second, and employs a 16-byte FIFO buffer to reduce loading on the host computer’s processor, so improving communications reliability. All serial cards are standard single-width podules, and are fully compatible with Atomwide 6 and 8-slot RiscPC backplanes. image: null - title: MIDI CARD subtitle: '' text: Allowed Archimedes systems to interact with any midi sound device. image: null emulators: - title: Arculator url: http://b-em.bbcmicro.com/arculator/ platform: Windows text: An excellent Windows-based Archimedes emulator, plays many games and has simple usage. - title: Red Squirrel url: http://www.red-squirrel.org/ platform: Windows text: An Emulator of Arm based Acorn machines for Windows 98/ME/2000/XP - title: Virtual Acorn url: http://www.virtualacorn.co.uk/ platform: Windows text: Excellent but commercial software - £30 - title: ARCHIE url: http://www.geocities.com/siliconvalley/campus/5427/ platform: Multiplatform text: Archie is an emulation of the Acorn Archimedes hardware (A3xx/A4xx/A3xxx) for DOS/Windows links: - title: The Hensa PD and Shareware Archive url: http://micros.hensa.ac.uk/micros/arch/riscos/arch-riscos.html text: '' docs: - title: TOM'S ARCHIMEDES DOCS (INTERNAL HARDWARE) url: http://b-em.bbcmicro.com/arculator/index.html cover: /media/museum/docs/couvs/vide.gif text: |- [**TOM'S ARCHIMEDES DOCS (INTERNAL HARDWARE)**](http://b-em.bbcmicro.com/arculator/index.html)written by Tom Mowalker  compiled/archived by Tom Mowalker\  type of document : HTML\  source : [Arculator](http://b-em.bbcmicro.com/arculator/index.html) comments: - author: Nick Broomfield (United Kingdom) date: Friday 1st April 2016 text: |- If you want to buy one! http://www.ebay.co.uk/itm/182075342752?ssPageName$STRK:MESELX:IT$\_trksid$p3984.m1555.l2649 - author: JHrn (USA) date: Friday 31st December 2010 text: |- I think it can do word processing, I had emulated RISC OS 3.x once, it\ had a built-in text editor, which is of course in the ROM. - author: Luca (Italy) date: Tuesday 11th May 2010 text: I own two of these :) - author: Erik N (Australia) date: Friday 8th June 2007 text: |- I think I want one of these\ does it do wordprocessing and printing??? - author: Merjia (Aus) date: Friday 11th August 2006 text: |- Yeah me too!\ They look awesome. - author: Pharoah (USA, PA) date: Friday 16th December 2005 text: |- Wow!\ I REALLY want one of these! related: - /museum/acorn-computer-archimedes - /museum/acorn-computer-archimedes-a3000 - /museum/acorn-computer-archimedes-a3010 - /museum/acorn-computer-archimedes-a3020 - /museum/acorn-computer-archimedes-a4000 - /museum/acorn-computer-archimedes-a5000 - /museum/acorn-computer-archimedes-a7000 oc_id: 31 source: url: https://web.archive.org/web/20230324065118/http://www.old-computers.com/museum/computer.asp?c=31 date: '2023-03-24' --- The Acorn A4 was the laptop version of the [Acorn Archimedes](/museum/acorn-computer-a4/) and was one of the first RISC laptops (and by the way, one of the most powerful - five times faster than a 50 MHz 486 for some operations). The operating system (RISC OS 3.10) was located in the 2 MB ROM. The 9'' LCD screen could only display 14 shades of grey, but used a clever dithering system to make more shades apparent. The A4 could be used for about 3 hours with its internal batteries. **Rob Kendrick** sent us more info :\ The case is actually an Olivetti laptop case, with an A5000 in it. Olivetti owned large chunks of Acorn at the time. The main difference between an A5000 (a desktop machine) and a A4 is that the A5000 had a 16MHz memory bus and a 33MHz ARM3. It had an advanced battery management unit that allows fine-grained control of the clock rate of the CPU (it can drop as low as 2MHz when the computer is idle and go back up to 24MHz when its busy) and the turning off of most of the hardware independently (such as the serial ports, floppy drive, hard drive etc) The filing system doesn't fragment. At all.