--- title: Acorn Computer Risc PC categories: - Computers types: - Professional Computer origins: - United Kingdom years: - '1994' cpus: - ARM 610 params: name: Risc PC image: /media/museum/photos/acorn_riscpc_system_s1.jpg company: /companies/acorn-computer company_name: Acorn Computer specs: - label: NAME value: Risc PC - label: MANUFACTURER value: Acorn Computer - label: TYPE value: Professional Computer - label: ORIGIN value: United Kingdom - label: YEAR value: '1994' - label: BUILT IN LANGUAGE value: BBC Basic - label: KEYBOARD value: Full 102 Key PS/2 PC style - label: CPU value: ARM 610 - label: SPEED value: 30 MHz - label: CO-PROCESSOR value: Choice of IBM-PC CPU’s including 486/586 - label: RAM value: 4 MB (Up to 256 MB) - label: ROM value: 4 MB containing most of the OS - label: GRAPHIC MODES value: Numerous - 1280 x 1024 at 256 colours, 800 x 600 16M colours - label: COLORS value: Full 24bit 16M colours (video memory permiting) - label: SOUND value: 16bit stereo 8 voice synthesiser (PC sound blaster compatible) - label: SIZE / WEIGHT value: 35.5 (W) x 38.5 (D) x 12 (H) cm - label: I/O PORTS value: Parallel, RS232, 2 x PS/2, VGA, 3.5mm sound jack, single width expansion slots (two per ‘slice’) - label: BUILT IN MEDIA value: 3.5'' floppy disk, 3.5'' IDE hard disk, CD-ROM - label: OS value: RISC OS 3.5 (mainly in ROM, aditional resources on hard disk) - label: POWER SUPPLY value: Built-in switching power supply unit - label: PRICE value: From around £1200 tabs: - photos - adverts - hardware forum_thread: 989 photos: - title: LARGE VIEW subtitle: '' text: The rounded front plastic cover slides inside the machine. image: /media/museum/photos/acorn_riscpc_system_s2.jpg - title: SIDE VIEW subtitle: '' text: A nice case design image: /media/museum/photos/acorn_riscpc_rightside_s1.jpg - title: RISC AND WINDOWS OS'S subtitle: '' text: The same machine could run alternately RISC OS-3.5 or MS-Dos/Windows OS's thanks to a second Intel processor card. image: /media/museum/photos/acorn_riscpc_dualos.jpg - title: REAR CONNECTORS subtitle: '' text: |- **(1)** Rsset switch\ **(2)** Stereo sound output jack\ **(3)** 15-pin video output plug\ **(4)** Keyboard mini-Din plug. Any standard PC/AT keyboard can be connected\ **(5)** Acorn mouse mini-Din plug\ **(6)** Expansion slots\ **(7)** Parallel printer DB25 connector\ **(8)** Serial DB9 connector. image: /media/museum/photos/acorn_riscpc_backside_s1.jpg - title: 'MAGIC CASE #1' subtitle: '' text: The base unit and the first 'slice' holding the floppy and CD-ROM drives. Up to eight slices could be stacked to expand the system. image: /media/museum/photos/acorn_riscpc_storageunit.jpg - title: 'MAGIC CASE #2' subtitle: '' text: '' image: /media/museum/photos/acorn_riscpc_inside_s2.jpg - title: 'MAGIC CASE #3' subtitle: '' text: This working system had 10 slices and an array of gadgets including a working pizza oven and remote controlled sink!!! More detailed information [here](http://www.worldofwibble.com/aboutriscpc.html). image: /media/museum/photos/acorn_riscpc_pizza.jpg - title: MAIN BOARD subtitle: '' text: |- **(1)** IDE hard disk, here a 1 GB model.\ **(2)** Floppy disk and hard disk connectors\ **(3)** IOMD20 - I/O controller and memory manager custom chipset\ **(4)** Connector of the ARM processor card\ **(5)** Connector of the Intel/PC processor card\ **(6)** Floppy disk and hard disk controller chipset\ **(7)** 256 MB ROM chips holding the RISC OS, here the 3.6 version\ **(8)** Network card connector\ **(9)** RAM module connectors\ **(10)** Video controller custom chipset\ **(11)** Backplane slot. Early RiscPCs came with the backplane for plugging in Podule cards. image: /media/museum/photos/acorn_riscpc_inside.jpg - title: PROCESSOR CARDS subtitle: '' text: The twin processor cards hold the ARM processor and the Intel-PC processor, here an ARM 710 and a Texas Instruments 486DX-4/100. image: /media/museum/photos/acorn_riscpc_proccards_s1.jpg adverts: - title: ADVERTISING PICTURE subtitle: '' text: '' image: /media/museum/pubs/acorn_riscpc_pub_s1.jpg hardware: - title: ARM 710 PROCESSOR CARD subtitle: '' text: '' image: /media/museum/hardware/acorn_riscpc_arm710card_s1.jpg - title: 486 PROCESSOR CARD subtitle: '' text: '' image: /media/museum/hardware/acorn_riscpc_486card_s1.jpg oc_id: 1015 source: url: https://web.archive.org/web/20230609185904/http://www.old-computers.com/museum/computer.asp?c=1015 date: '2023-06-09' --- In April 1994, Acorn announced the release of the second generation of ARM machines – the Acorn RISC PC 600. Code named the **Medusa** project, this was set to replace the then ailing flagship [A5000](/museum/acorn-computer-archimedes-a5000/) machine. As the name suggests, one of the main features of this computer was that it could run both Acorn and IBM-PC software side by side. This was achieved by a second CPU slot that could accept a daughter board with a PC CPU, such as a 486 or 586. This second processor then had shared access with the primary CPU to all the system resources. No more CPU intensive software PC emulation required! As well as the second processor, other major enhancements included an updated video controller with the option for dedicated video RAM. The graphics chip in previous Archimedes range machines had shared the system memory with the rest of the computer which often proved to be a bottle neck without true DMA. Now the video controller could have video memory of it’s own, removing the bottle neck. The system data bus was doubled in size to 32bits wide, and the MEMU and IOC chips were combined to create the IOMD20. This resulted in much better overall I/O, yet another bottle neck removed from previous machines. The system memory was also upgraded to a maximum of 256MB and the memory bus was designed to use the more widely available EDO SIMM’s. A unique feature of the RISC PC was its case. This came in the form of the base holding the motherboard and power supply, a mid section for mounting one 3.5" device, one 5.25" device and two single width expansion cards, and then a lid. The magic was that you could add up to 8 slices at any time, giving you a very easily expandable computer, and all held together with clips and springs negating the need for a screwdriver. Very neat. There were 2 other Acorn RISC PC's. The RISC **PC 700** was released July 1995 and the RISC **PC-2** was much publicised by Acorn and then dramatically cancelled at the last minute. Thanks to **Paul Hadfield** for his kind help.