RISC iX

RISC iX is a discontinued Unix operating system designed to run on a series of workstations based on the Acorn Archimedes microcomputer.[1] Heavily based on 4.3BSD, it was initially completed in 1988 – a year after Arthur but prior to RISC OS.[2] It was introduced in the ARM2-based R140 workstation in 1989,[3] followed up by the ARM3-based R200-series workstations in 1990.[4]

RISC iX
RISC iX running on the Acorn A680
DeveloperAcorn Computers Ltd
OS familyUnix-like
Working stateHistoric
Initial release1988 (1988)
PlatformsAcorn Archimedes
Default user interfaceGraphical user interface

Features

RISC iX 1.2 upgraded the X11 server to release 4, and was certified to conform to the X/Open Portability Guide 3 Base profile.[6][7]

The native file system implemented a transparent executable file compression mechanism[8][9](pp69) that took advantage of the hardware's 32 KB page size and sparse files.[10] Despite this, the workstations offering RISC iX were regarded as being hampered by the memory management unit (MMU) using 32 KB pages.[11] The hardware supporting RISC iX also did not have direct memory access capabilities for disk operations, meaning that the CPU would spend time servicing interupts related to disk transfers resulting in "a definite reduction in, but not a complete loss of, available CPU power during disc transfers".[12]

Additionally, the console featured a two-cursor text copying mechanism inspired by Acorn's own earlier 8-bit range including the BBC Micro.[13]

Distribution

RISC iX was either supplied preinstalled on new computer hardware or was installed onsite from a portable tape drive by Granada Microcare, who would take the installation tape away with them. Upgrades to RISC iX 1.2 from earlier versions started at £349 for R140 machines, and new installations for A400-series machines started at £999.[6] Installations required 100 MB of space on suitable hard drive or network storage, with hard drive and SCSI card bundles being offered from £1699 for R140 machines and from £2326 for A400-series machines.[14]

Once installed a backup of the core operating system to three floppy disks was possible, allowing future reinstallation.

Supported hardware

According to documentation concerning RISC iX 1.2 availability, the operating system could be used on the R140, R225 and R260, being pre-installed on the R260, accessible via a fileserver (such as an R260) on the R225, and as an upgrade from RISC iX 1.15 or earlier on the R140. The A540, being practically identical to the R260,[15] could support RISC iX as delivered, whereas A400-series machines required an Acorn SCSI card, with older A400-series machines also needing a memory controller upgrade and "all the appropriate field change orders" to have been performed. A300-series and the A3000 machines were not supported.[14]

RISC iX is not compatible with later Archimedes machines.

Machines

A number of machines were designed specifically to run RISC iX.

Acorn A680 and Acorn R140

M4

An unreleased machine, built internally by Acorn for the development of RISC iX. Reputedly only three were built and one of them has subsequently been destroyed. All known examples are owned by The National Museum of Computing.

A680 Technical Publishing System

Unreleased but widely prototyped, the A680 contained an ARM2 processor, 8 MB RAM (dual MEMCs) and a 67 MB hard drive running from an onboard SCSI controller (no other machine from Acorn Computers included integrated SCSI). It is rumoured that overheating from the SCSI controller was one reason for the machine to never be released.

R140

Based on the A440/1, the R140 uses the same 8 MHz ARM2 processor and 4 MB RAM, also providing a 60 MB ST506 hard drive, with the option of adding a second hard drive using the same internal controller. A SCSI adaptor was available (priced at £299 plus VAT) for other storage peripherals. Since the hardware is based on the Archimedes series, Acorn's podule expansions could be added, although appropriate drivers would have needed to be written.[9](pp47)

At the time of initial release in 1989, the cost of the R140 was £3,500 for a standalone workstation without Ethernet connectivity. For the additional cost of the Ethernet expansion (£449 plus VAT), a network-capable workstation could be configured. A floating point expansion card based on the WE32206 could also be added (priced at £599 plus VAT).[16] A discount introduced at the start of 1990 offered the R140 bundled with Ethernet expansion and either a 14-inch colour monitor with PC emulation software or a 19-inch monochrome monitor for £2999 plus VAT.[17]

Supplied with RISC OS 2 in ROM, the machine would boot that OS then could either automatically boot RISC iX totally removing RISC OS from memory or continue running RISC OS – optionally being rebooted into RISC iX at any time.[18]

An ordinary A440/1 with at least 4 MB RAM and a suitable hard drive could also run RISC iX.[14]

R260

Based on the A540,[19] the R260 originally contained a 26 MHz, (later 33 MHz) ARM3 processor, 8 MB RAM (upgradable to 16 MB) SCSI adapter and a 100 MB[4][11] or 120 MB[20] SCSI hard drive (typically a Conner CP30100). It booted in the same style as the earlier R140, but was normally configured for customers to boot straight into RISC iX.[21] The machine was supplied with an Ethernet adapter.

The system was released in 1990 priced at £3995 plus VAT,[22] having been announced with a price of £5000 plus VAT.[4]

A similarly configured A540 could run RISC iX.[14]

R225

The R225 was a diskless version of the R260. It required a network file server or an R260 to boot.[14]

The system was released alongside the R260 priced at £1995 plus VAT,[22] having been announced with a price of £3000 plus VAT.[4]

Peripherals

As well as industry-standard Ethernet, Acorn's own Econet was supported, facilitating connectivity between Econet and IP-based Ethernet networks.[23] Moreover, the Econet interface on a RISC iX workstation could be treated as a "Unix networking" interface, permitting TCP/IP requests to be sent over Econet to hosts capable of handling them.[24] Similar Econet gateway capabilities were eventually extended to computers running RISC OS with Acorn Universal Networking (AUN),[25] and a device driver update eventually provided a similar means of routing TCP/IP communications over Econet networks for RISC OS machines.[26]

Applications Software

In 1989, Acorn announced support for the R140 from a number of application software vendors, including Informix. along with applications such as Uniplex, Q-Office (from Quadratron), Tetraplan, Sculptor (from MPD), Sea Change (from Thomson),[27] Recital ("a dBase compatible relational database") and Q-Calc ("a Lotus, key-compatible spreadsheet").[28] Applications for school administration and financial management - SIMS and SCRIPT - were also offered in a bundle with the R140 workstation.[29]

References
  1. Acorn R140 RISC iX User Guide (PDF). Acorn Computers Limited. December 1988. ISBN 1852500581.
  2. Chris's Acorns: RISC iX
  3. "Acorn to unveil Unix machine". Acorn User. February 1989. p. 7. Retrieved 6 September 2020.
  4. "ARM3-based Unix". Acorn User. August 1990. p. 7. Retrieved 25 October 2020.
  5. Acorn R140 workstation in commercial and technical applications (PDF) (1 ed.). January 1989.
  6. "Arc Unix at Low Cost". Acorn User. August 1991. p. 7. Retrieved 23 December 2020.
  7. Acorn Computer Products June 1991 (PDF). Acorn Computers Limited. May 1991. p. 2. Retrieved 16 October 2020.
  8. Taunton, Mark (1991). "Compressed Executables: An Exercise in Thinking Small". Proceedings of the Summer 1991 USENIX Conference, Nashville, TE, USA, June 1991. USENIX Association: 385–404.
  9. Cox, James (December 1989). "Power to the People". Acorn User. pp. 66–67, 69, 71. Retrieved 6 September 2020.
  10. Taunton, Mark (22 January 1991). "Compressed executables". Newsgroup: comp.unix.internals. Usenet: 4743@acorn.co.uk. Retrieved 10 October 2020.
  11. "Acorn R260" (PDF). Personal Computer World. August 1990. pp. 148–152. Retrieved 6 September 2020. A current flaw is that the 32k page size is really too big. Once paging gets going, the decline in performance is less than graceful.
  12. "MEMC and video DMA question". Newsgroup: comp.sys.acorn. 14 February 1991. Retrieved 8 January 2021. There is no separate DMA hardware for any other data traffic. The built-in ST506 controller in the A4x0/R140 has its own buffering, and the processor is required to transfer the data under interrupt on each 256-byte sector boundary, or once every 500 microseconds or so during a multi-sector transfer.
  13. Acorn R140 Operations Guide (PDF). Acorn Computers Limited. December 1988. p. 63. ISBN 1852500573. Retrieved 17 October 2020. Selecting BBC mode gives you access to a very useful mechanism called cursor copy action. This was originally developed for the BBC Microcomputer, which is why it ts termed BBC mode.
  14. RISCiX 1.2 Upgrade Products (Technical report). Acorn Computers Limited. Retrieved 10 October 2020.
  15. James, Paul; Bell, Graham (November 1990). "Five's Alive". Acorn User. p. 21. Retrieved 22 October 2020. In essence, the machine is identical to the R260 Unix workstation, but comes without Unix and without the built-in Ethernet of the latter machine.
  16. R140 Computer Systems (PDF) (3 ed.). Acorn Computers Limited. June 1989. Retrieved 6 September 2020.
  17. "Cheap Workstation". Acorn User. February 1990. p. 7. Retrieved 24 December 2020.
  18. Redfern, Andy (March 1989). "Acorn R140" (PDF). Personal Computer World. p. 128. Retrieved 23 October 2020. On switching the machine on you are booted almost instantly into RISC OS. [...] Clicking on the Unix icon activates a dialogue box asking if you really want to go into Unix or not. By clicking on the middle of this box a number of parameters can be set up. For example, you can disable RISC OS completely so that next time you switch the machine on it boots straight into Unix, or you can specify a slow boot which performs all the disk and file checking.
  19. Acorn Archimedes 500 series Acorn R200 series Service Manual (PDF). Acorn Computers Limited. June 1991. pp. vi. ISBN 185250093X.
  20. Acorn R260 (PDF) (1 ed.). Acorn Computers Limited. August 1992. p. 2. Retrieved 8 September 2020.
  21. Pountain, Dick (December 1990). "A RISC Workstation from Acorn" (PDF). Byte. pp. 72IS–15. As normally delivered to customers, though, the R260 boots straight into RISCiX multi-user mode; you never see RISC OS. To enter RISC OS, you must log out of Unix by typing halt -RISCOS.
  22. "Acorn Newsletter" (PDF) (16). Acorn Computers Limited. 1990. p. 1.
  23. Connectivity from Acorn (PDF). Acorn Computers Limited. September 1989. p. 5. Retrieved 16 October 2020. The R140, which is connected between the Ethernet and Econet networks, provides an internet routing service between the two.
  24. RISC-iX Group, Acorn Computers, Cambridge, UK. Acorn Unix Econet Device Driver and Network Device (PDF) (Technical report). Acorn Computers Limited. Retrieved 16 October 2020.CS1 maint: multiple names: authors list (link)
  25. "Acorn introduces Universal Networking" (Press release). An Acorn Universal Network can consist of a number of Econet and Ethernet networks linked together via a backbone Ethernet network using RISC OS computers as Gateway stations. These computers can act at the same time as local fileservers.
  26. "New EconetA module available" (Press release). Xemplar Education Limited. EconetA is a driver module that allows Econet and Nexus client computers to act as full TCP/IP clients as well as enabling gatewaying between the above systems and standard Ethernet installations.
  27. "Informix signs up for R140". Acorn User. April 1989. p. 7. Retrieved 23 October 2020.
  28. "Acorn Unix puts on a good show". Acorn User. August 1989. p. 7. Retrieved 1 November 2020.
  29. "Unix for schools". Acorn User. June 1989. p. 15. Retrieved 23 October 2020.
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