Acorn R260
 | |
| An R260 with its monitor and PC-style keyboard (photo: Chris Whytehead, CC BY-SA 3.0) | |
| Specifications | |
|---|---|
| Manufacturer | Acorn Computers |
| Type | Unix workstation |
| Released | 1990 |
| Discontinued | 1993 |
| Intro price | £3,995 ex VAT |
| CPU | ARM3 (30 MHz on Chris Whytehead's machine) on a plug-in processor card |
| Memory | 8 MB, expandable to 16 MB with RAM cards |
| Storage | SCSI hard disc (100 MB; 120 MB formatted in Acorn's 1992 leaflet); 3.5-inch floppy drive |
| Display | VIDC1a; analogue RGB up to 800 × 600, and 1152 × 900 monochrome |
| Sound | — |
| OS / Firmware | RISC iX 1.2 (4.3BSD Unix), with RISC OS in ROM |
| Predecessor | Acorn R140 |
| Model no. | UNX26 |
The Acorn R260 is an ARM3 Unix workstation that Acorn Computers sold from 1990 to 1993.[1] It is the hardware of the Acorn Archimedes A540 with 8 MB of RAM, a SCSI hard disc, an Ethernet card and RISC iX 1.2 pre-installed.[2][3] The Acorn R225 is the same machine without discs, booting over the network.
Acorn documented the A540, R260 and R225 together, so the hardware detail on the Acorn Archimedes A540 page applies here: the processor card, memory cards, video, power supply table, polarised capacitor list and the NiCd backup battery.[4]
History
[edit | edit source]Wikipedia gives the R260's launch price as £3,995 ex VAT, down from an announced £5,000, and records that the A540 and R260 were discontinued in mid-1993.[1] Acorn released the FPA10 floating point accelerator for the A540, A5000 and R260 in July 1993. Owners of early R260s might need a free modification to the processor card before fitting one, and RISC iX needs an extra driver for it.[5] Chris Whytehead measured 310 kWhetstones on his R260 with its 30 MHz ARM3, and 2,807 with a 25 MHz ARM3 and an FPA10 fitted instead.[2]
Configuration
[edit | edit source]| Item | Specification |
|---|---|
| Processor | ARM3, quoted at 13.5 MIPS |
| Memory | 8 MB, expandable to 16 MB with RAM cards |
| ROM | 2 MB (RISC OS) |
| Storage | 120 MB formatted SCSI hard disc; 1 MB (unformatted) 3.5-inch floppy drive |
| Keyboard and mouse | 103-key PC AT style keyboard; three-button mouse |
| Interfaces | Parallel, serial, SCSI and Ethernet as standard; 3.5 mm stereo jack; two free expansion slots |
| Display | Analogue RGB 640 × 256 and VGA 640 × 480 in up to 256 colours; Super VGA 800 × 600 in 16 colours; 1152 × 900 monochrome |
| Software | RISC iX 1.2 (X/Open XPG3), X Window System, X.desktop, TCP/IP, NFS 4.0 and ONC, C, Pascal and Fortran 77 |
The 1992 figures differ from the launch machines. Chris Whytehead's R260 has a 100 MB Conner CP3100 and RISC OS 2.01 ROMs dated 5 July 1990, and Wikipedia gives the disc as 100 or 120 MB.[2][1] His machine also measures 15.84 MIPS with ARMSi, against Acorn's 13.5.[2]
The main board carries 4 MB, so an 8 MB R260 has one 4 MB RAM card in SK5 to SK7, and each card carries its own MEMC1a.[4] Acorn fitted a SCSI card and an Ethernet card to the R260 as standard, which leaves two of the four slots free.[3] Chris Whytehead's R260 has the AKA31 SCSI and AKA25 Ethernet cards.[2]
Ethernet card
[edit | edit source]Acorn's service manual describes two Ethernet cards for these machines, Ethernet I and Ethernet II, both of which support thick Ethernet or thin Ethernet (Cheapernet). The Ethernet I card uses the Intel 82586 network controller, 82501 serial interface and 82502 transceiver, with an AUI D-type socket and a PROM holding the card's extended podule ID. On the Ethernet I card, links LK1 and LK2 select the buffer RAM size (both south for the normal 32 KB devices) and LK3 to LK8 choose thick Ethernet (west, pins a to b) or Cheapernet (east, pins b to c).[4]
RISC iX
[edit | edit source]The R260 starts in RISC OS and boots RISC iX from the hard disc. To boot straight into RISC iX, set *CONFIGURE noRISCOS.[6] If the machine boots into RISC OS but shows no RISC iX icon, open the hard disc's root directory and double-click !RISCiX. If it still will not boot RISC iX, Acorn refers to the chapter on the RISCiXFS module in the RISC iX System Administrator's Guide.[6]
A DELETE power-on, holding DELETE until the self-test has finished, restores the factory CMOS settings. Acorn's guide then lists the default settings to check, including FileSystem SCSI, SCSIFSDiscs 1 and SCSIFSDrive 4, and has the user set the monitor and sync types again before the desktop will display.[6]
Warning: Acorn's SCSI drive test reformats the hard disc and destroys its contents, which on an R260 includes RISC iX.[4] Back up first; see Hard Drive Maintenance and Repair.
Maintenance
[edit | edit source]- Remove and inspect the 1.2 V NiCd backup cell BT1 before powering a machine that has been stored. The cell, its check and the board around it are described on the A540 page; see also Battery Explosion, Capacitor or Corrosion Damage.
- The power supply has a filter on one side for the air drawn in by its two fans. Acorn says to clean it at least once a year: vacuum the grille, pull the filter out by its tab, vacuum and tap it clean and refit it with the frame on the outside. The replacement filter is Acorn part 0816,017.[6]
- Check that both power supply fans turn, and measure the rails against the table on the A540 page.
Fault finding
[edit | edit source]Acorn's installation guide says that if the self-test does not complete, or the screen stays red, there may be a fault with the memory.[6] The service manual explains what the self-test is doing.[4]
| Screen | Stage |
|---|---|
| Purple | Testing has started: brief ROM and RAM test, I/O and video controllers initialised. A crash here, or a purple screen that stays, points to a major fault, probably in the I/O system |
| Blue | The simple memory test passed; the longer memory test runs, up to 12 seconds on a 16 MB machine |
| Purple again | VIDC and sound timing tests, then the ARM 3 identification test |
| Black, with a memory size message | Self-test complete; RISC OS starts |
| Red, with the floppy drive light flashing | A fault was found. The light flashes an 8-digit hexadecimal code as 8 groups of 4 flashes, long for 1 and short for 0 |
| Green | Shown with the result code when the test link is fitted; a pass if it follows the purple and blue screens |
The self-test sets a 15 kHz screen mode, so a VGA or high-resolution monitor will not synchronise during it.[4] The self-test normally runs only from power-on. A test link, a 1N4148 diode fitted to the six-pin link LK4 near the RAM card sockets, forces it on every reset and always displays the result code.[4]
| Bit | Meaning |
|---|---|
| 00000200 | ROM failed checksum test |
| 00000900 (as printed) | MEMC CAM mapping failed |
| 00000800 | MEMC protection failed |
| 00004000 | VIDC (Virq interrupt) timing failed |
| 00008000 | Sound (Sirq interrupt) timing failed |
| 00020000 | RAM control line failure |
| 00040000 | Long RAM test failure |
Bits 0 to 7 are status flags and are not faults: 01 power-on, 02 interface hardware, 04 test link, 08 long memory test performed, 10 ARM 3 fitted. The manual's own example is a ROM failure on an ARM3 machine, shown as 00000219.[4] For component-level work, Acorn's procedure for a dead machine swaps the processor card, the master MEMC, IOC and VIDC in turn; see the A540 page and the hosted service manual and circuit diagrams.
Documentation
[edit | edit source]- Acorn Archimedes 500 Series and R200 Series Service Manual: part 0486,056, issue 2, June 1991, covering the A540, R260 and R225.
- Acorn R200 Series Documentation: the A540, R260 and R225 Installation Guide (0486,251), the APP480 leaflet, and twelve circuit and assembly drawings for the main board, RAM card, ARM3 card, backplane, keyboard, Ethernet II and SCSI cards.
- Personal Computer World reviewed the R260 in August 1990; Chris's Acorns has the scan.[2]
Gallery
[edit | edit source]-
ARM3 processor card and RAM cards from Chris Whytehead's R260 -
Acorn's drawing of the front of the system unit
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Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 1.2 "RISC iX", Wikipedia (retrieved 2026-10-02). Sections "Hardware" (R260 based on the A540 with a 30 MHz ARM3, 8 MB, SCSI and a 100 or 120 MB disc, released in 1990 at £3,995 plus VAT after an announced £5,000; FPA10 from 1993 at £99; A540 and R260 discontinued in mid-1993; R225 at £1,995 plus VAT after an announced £3,000) and "Legacy".
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Whytehead, Chris. "RISC iX Computers", Chris's Acorns, The Centre for Computing History (retrieved 2026-10-02). R260 "functionally identical to the A540", 8 MB and a 100 MB SCSI disc as standard, ARM3 and Ethernet; product UNX26; his R260 (serial 01-UNX26-1000012, main board 0186,000 issue 1, backplane 0186,001 issue 1, VL86C020 ARM3 at 30 MHz, 16 MB, Conner CP3100, Citizen OSDC-65C, RISC OS 2.01 of 5 July 1990, AKA25 Ethernet and AKA31 SCSI cards; 23,805 Dhrystones, 15.84 MIPS; 2,807 kWhetstones with a 25 MHz ARM3 and FPA10 in place of the 30 MHz ARM3); R225 released in June 1990; PCW review of August 1990.
- ↑ 3.0 3.1 Acorn Computers, Acorn R260, leaflet APP 480, first edition, August 1992. Hosted on this wiki: File:Acorn R260 leaflet (APP480).pdf. ARM3 at 13.5 MIPS, RISC iX 1.2, 8 MB expandable to 16 MB, 2 MB ROM, 120 MB formatted SCSI hard disc, 1 MB floppy, 103-key PC AT keyboard, three-button mouse, SCSI and Ethernet standard, two free expansion slots, display modes.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Acorn Computers, Acorn Archimedes 500 series / Acorn R200 series Service Manual, part no. 0486,056, issue 2, June 1991. Hosted on this wiki: Acorn Archimedes 500 Series and R200 Series Service Manual. Models covered (About this manual); Ethernet I and II expansion cards (part 2, pp. 2-1 to 2-17); disassembly notes on the R225 (p. 3-1); power-on self-test, test link and result codes (pp. 5-1 to 5-9).
- ↑ Acorn Computers Limited, press release "Acorn Releases Floating Point Accelerator", 5 July 1993. Text via Chris's Acorns.
- ↑ 6.0 6.1 6.2 6.3 6.4 Acorn Computers, Installation Guide for the A540, R260 and R225, part no. 0486,251, issue 1, July 1990. Hosted on this wiki: Acorn R200 Series Documentation. If things go wrong (pp. 15 to 17); front of the computer (p. 63); Ethernet and expansion cards (Appendices A and D); cleaning the fan filter (pp. 110 and 111).