yann64andClaude Opus 5.5
b274874139
1,289 discussions, 9,527 archived comments; pages no longer carry the comments themselves. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01YDRjtmAiNpo5mK5N3d7QwZ
200 lines
7.4 KiB
Markdown
200 lines
7.4 KiB
Markdown
---
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title: Acorn Computer A4
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categories:
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- Computers
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types:
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- Portable
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origins:
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- United Kingdom
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years:
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- '1991'
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cpus:
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- ARM 3
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params:
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name: A4
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image: /media/museum/photos/acorn_a4_running_s1.jpg
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company: /companies/acorn-computer
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company_name: Acorn Computer
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specs:
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- label: NAME
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value: A4
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- label: MANUFACTURER
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value: Acorn Computer
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- label: TYPE
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value: Portable
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- label: ORIGIN
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value: United Kingdom
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- label: YEAR
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value: '1991'
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- label: KEYBOARD
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value: 84 keys with arrow keys
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- label: CPU
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value: ARM 3 (with 4 KB of internal RAM cache)
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- label: SPEED
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value: 24 mHz (internal CPU) and 12 mHz (bus)
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- label: RAM
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value: 4MB
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- label: ROM
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value: 2 MB
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- label: TEXT MODES
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value: 'Max : 132 x 30'
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- label: GRAPHIC MODES
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value: 47 graphic modes, maximum 640 x 480 with LCD screen and up to 1152 x 896 with VGA screen
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- label: COLORS
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value: 14 shades of grey (LCD screen)
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- label: SOUND
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value: 8 voices (stereo 8 bit)
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- label: I/O PORTS
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value: VGA, Centronics, RS232 C, stereo sound, Mouse, Keyboard
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- label: BUILT IN MEDIA
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value: one 3.5'' disk-drive
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- label: OS
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value: RISC OS 3.10
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- label: POWER SUPPLY
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value: External PSU
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- label: PRICE
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value: £1395 (2Mb floppy version) up to £1895 (4Mb HD120 version)
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tabs:
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- photos
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- hardware
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- emulators
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- links
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- docs
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forum_thread: 50
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photos:
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- title: ACORN A4
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subtitle: ''
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text: The A4 used a slightly modified version of the Olivetti M15 laptop case.
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image: /media/museum/photos/acorn_a4_running_s2.jpg
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- title: TOP VIEW
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subtitle: ''
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text: ''
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image: /media/museum/photos/acorn_a4_topview_s1.jpg
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- title: BOTH SIDES
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subtitle: ''
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text: |-
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On the right hand side:\
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• 3.5" floppy disk drive\
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• Stereo headphone jack\
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• External standard AT keyboard mini-DIN socket\
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• Acorn mouse mini-DIN socket\
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• Serial RS232 DB9 connector
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On the left hand side:\
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• Battery pack\
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• Trap door allowing to exchange ROM and RAM chips.
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image: /media/museum/photos/acorn_a4_sides_s1.jpg
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- title: REAR CONNECTORS
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subtitle: ''
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text: |-
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From left to right:\
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• 2nd serial port\
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• External PSU connector\
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• Standard VGA 15-pin video output.
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image: /media/museum/photos/acorn_a4_rearcon_s1.jpg
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- title: INSIDE
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subtitle: ''
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text: Note the battery pack, the slim size Epson floppy disk drive and the Conner 3.5" 60 MB hard disk drive.
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image: /media/museum/photos/acorn_a4_inside_s1.jpg
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- title: MOTHERBOARD
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subtitle: ''
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text: |-
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**(1)** LCD display connectors\
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**(2)** VLSI Arm co-processors. They manage I/O's, video, memory, FDD & HDD.\
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**(3)** Hard drive connector\
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**(4)** Floppy drive connector\
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**(5)** ARM 3 processor\
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**(6)** RISC OS 3.10 ROMs\
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**(7)** 4 MB RAM chips.
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image: /media/museum/photos/acorn_a4_mainboard_s1.jpg
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hardware:
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- title: 486 CARD
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subtitle: ''
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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
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image: /media/museum/hardware/acorn_a39000_486card_1.jpg
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- title: GRAPHICS ACCELERATOR
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subtitle: ''
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text: |-
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Graphics accelerator card (called "ColourCard") for A3000, Archimedes and A5000.\
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Company : Computer Concepts\
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Enhanced potential for Archimedes series including 15-bit desktop modes (i.e. 800\*600 @ 256 colours).
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Thanks to **Chris Syntichakis**
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image: /media/museum/hardware/acorn_a5000_colorcard_1.jpg
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- title: CUMANA SCSI CARD
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subtitle: ''
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text: |-
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16-bit SCSI-1 card\
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Company: Cumana.\
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There are an external port for scanners/CD-ROM etc. and 2 internal ports for SCSI and Floptical drives.
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Thanks to **Chris Syntichakis**
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image: /media/museum/hardware/acorn_a5000_scsicard_1.jpg
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- title: SERIAL CARD
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subtitle: ''
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text: |-
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From Atomwide's site:\
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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.
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image: /media/museum/hardware/acorn_a5000_serialcard_1.jpg
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- title: MIDI CARD
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subtitle: ''
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text: Allowed Archimedes systems to interact with any midi sound device.
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image: /media/museum/hardware/acorn_a4000_midicard_s1.jpg
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emulators:
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- title: Arculator
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url: http://b-em.bbcmicro.com/arculator/
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platform: Windows
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text: An excellent Windows-based Archimedes emulator, plays many games and has simple usage.
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- title: Red Squirrel
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url: http://www.red-squirrel.org/
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platform: Windows
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text: An Emulator of Arm based Acorn machines for Windows 98/ME/2000/XP
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- title: Virtual Acorn
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url: http://www.virtualacorn.co.uk/
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platform: Windows
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text: Excellent but commercial software - £30
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- title: ARCHIE
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url: http://www.geocities.com/siliconvalley/campus/5427/
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platform: Multiplatform
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text: Archie is an emulation of the Acorn Archimedes hardware (A3xx/A4xx/A3xxx) for DOS/Windows
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links:
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- title: The Hensa PD and Shareware Archive
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url: http://micros.hensa.ac.uk/micros/arch/riscos/arch-riscos.html
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text: ''
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docs:
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- title: TOM'S ARCHIMEDES DOCS (INTERNAL HARDWARE)
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url: http://b-em.bbcmicro.com/arculator/index.html
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cover: /media/museum/docs/couvs/vide.gif
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text: |-
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[**TOM'S ARCHIMEDES DOCS (INTERNAL HARDWARE)**](http://b-em.bbcmicro.com/arculator/index.html)written by Tom Mowalker
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compiled/archived by Tom Mowalker\
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type of document : HTML\
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source : [Arculator](http://b-em.bbcmicro.com/arculator/index.html)
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related:
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- /museum/acorn-computer-archimedes
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- /museum/acorn-computer-archimedes-a3000
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- /museum/acorn-computer-archimedes-a3010
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- /museum/acorn-computer-archimedes-a3020
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- /museum/acorn-computer-archimedes-a4000
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- /museum/acorn-computer-archimedes-a5000
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- /museum/acorn-computer-archimedes-a7000
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oc_id: 31
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source:
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url: https://web.archive.org/web/20230324065118/http://www.old-computers.com/museum/computer.asp?c=31
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date: '2023-03-24'
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---
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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).
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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.
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The A4 could be used for about 3 hours with its internal batteries.
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**Rob Kendrick** sent us more info :\
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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.
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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)
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The filing system doesn't fragment. At all.
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