website/content/museum/acorn-computer-a4.md

title, categories, types, origins, years, cpus, params

title	categories	types	origins	years	cpus	params
Acorn Computer A4	Computers	Portable	United Kingdom	1991	ARM 3	name image company company_name specs tabs forum_thread photos hardware emulators links docs related oc_id source A4 /media/museum/photos/acorn_a4_running_s1.jpg /companies/acorn-computer Acorn Computer label value NAME A4 label value MANUFACTURER Acorn Computer label value TYPE Portable label value ORIGIN United Kingdom label value YEAR 1991 label value KEYBOARD 84 keys with arrow keys label value CPU ARM 3 (with 4 KB of internal RAM cache) label value SPEED 24 mHz (internal CPU) and 12 mHz (bus) label value RAM 4MB label value ROM 2 MB label value TEXT MODES Max : 132 x 30 label value GRAPHIC MODES 47 graphic modes, maximum 640 x 480 with LCD screen and up to 1152 x 896 with VGA screen label value COLORS 14 shades of grey (LCD screen) label value SOUND 8 voices (stereo 8 bit) label value I/O PORTS VGA, Centronics, RS232 C, stereo sound, Mouse, Keyboard label value BUILT IN MEDIA one 3.5'' disk-drive label value OS RISC OS 3.10 label value POWER SUPPLY External PSU label value PRICE £1395 (2Mb floppy version) up to £1895 (4Mb HD120 version) photos hardware emulators links docs 50 title subtitle text image ACORN A4 The A4 used a slightly modified version of the Olivetti M15 laptop case. /media/museum/photos/acorn_a4_running_s2.jpg title subtitle text image TOP VIEW /media/museum/photos/acorn_a4_topview_s1.jpg title subtitle text image BOTH SIDES 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. /media/museum/photos/acorn_a4_sides_s1.jpg title subtitle text image REAR CONNECTORS From left to right:\ • 2nd serial port\ • External PSU connector\ • Standard VGA 15-pin video output. /media/museum/photos/acorn_a4_rearcon_s1.jpg title subtitle text image INSIDE Note the battery pack, the slim size Epson floppy disk drive and the Conner 3.5" 60 MB hard disk drive. /media/museum/photos/acorn_a4_inside_s1.jpg title subtitle text image MOTHERBOARD **(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. /media/museum/photos/acorn_a4_mainboard_s1.jpg title subtitle text image 486 CARD 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 /media/museum/hardware/acorn_a39000_486card_1.jpg title subtitle text image GRAPHICS ACCELERATOR 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** /media/museum/hardware/acorn_a5000_colorcard_1.jpg title subtitle text image CUMANA SCSI CARD 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** /media/museum/hardware/acorn_a5000_scsicard_1.jpg title subtitle text image SERIAL CARD 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. /media/museum/hardware/acorn_a5000_serialcard_1.jpg title subtitle text image MIDI CARD Allowed Archimedes systems to interact with any midi sound device. /media/museum/hardware/acorn_a4000_midicard_s1.jpg title url platform text Arculator http://b-em.bbcmicro.com/arculator/ Windows An excellent Windows-based Archimedes emulator, plays many games and has simple usage. title url platform text Red Squirrel http://www.red-squirrel.org/ Windows An Emulator of Arm based Acorn machines for Windows 98/ME/2000/XP title url platform text Virtual Acorn http://www.virtualacorn.co.uk/ Windows Excellent but commercial software - £30 title url platform text ARCHIE http://www.geocities.com/siliconvalley/campus/5427/ Multiplatform Archie is an emulation of the Acorn Archimedes hardware (A3xx/A4xx/A3xxx) for DOS/Windows title url text The Hensa PD and Shareware Archive http://micros.hensa.ac.uk/micros/arch/riscos/arch-riscos.html title url cover text TOM'S ARCHIMEDES DOCS (INTERNAL HARDWARE) http://b-em.bbcmicro.com/arculator/index.html /media/museum/docs/couvs/vide.gif [**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) /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 31 url date https://web.archive.org/web/20230324065118/http://www.old-computers.com/museum/computer.asp?c=31 2023-03-24

The Acorn A4 was the laptop version of the Acorn Archimedes 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.