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Acorn Archimedes A540

[A400/1 ]     [Archimedes ]     [A3000 ]


 In June 1990 Acorn lauched the A540 which was the flagship of the Archimedes range. It had 4MB RAM by default but could be expanded to 16MB with additional RAMcards, each with its own 4MB RAM and MEMC1a. Unlike the rest of the range it had a SCSI podule as standard and a 100MB hard disc. The A540 was launched with RISC OS 2.01. Finally it had an ARM3 CPU on a card which could take an FPA10 floating point accelerator.

Overall the A540 is a very powerful computer for its time and, indeed, it was Acorn's top of the range, flagship model for some time. It was the only Acorn computer which could be expanded to 16MB and the ARM3 CPU + FPA made it more powerful than the A5000. I find it a little tempramental if not used for a while. The memory cards in particular are liable to get dislodged.

The A540 hardware was the same as the R260   except that RISCiX was not installed; it could of course be purchased seperately and installed on an A540.

The following model was produced [that I know of]:

Manuals and documents

Here is the Archimedes 540 product brochure:
Archimedes A540 brochure 

Here is the R260, R225, A540 Installation Guide 

Here is the Archimedes 500 Acorn R200 Service Manual. and technical drawings.

Here is the Archimedes 500 Acorn R200 Technical Reference Manual and technical drawings .


I could never afford an A540 at the time, it cost £2495 + VAT and did not include a monitor. I bought my first A540 on ebay in 2002. I bought the second A540 from an ex-Acorn employee in 2004.

A540 (No. 1)

The first A540 has been been substantially upgraded. It now has 16MB RAM, 4MB on the motherboard and 3 x 4MB on RAM cards. The CPU is an 33MHz  ARM3, rather than the original 25MHz model. It has an FPA10 floating point accelerator on the CPU card. It runs RISC OS 3.11 and has the Acorn Universal Boot installed. It has an Acorn AKA31 SCSI Interface  with 2 SCSI discs, the first for RISC OS and the second with the PC emulator and a DOS partition. The Atomwide Ethernet IV card  is working and Internet 5 is installed in the Universal Boot, Share FS is enabled to share a read only public directory. A Computer Concepts Colour Card Gold is installed to improvce the graphics. A Computer Concepts ScanLight card  is also installed, but although I have the scanner for it I have not used it recently.

Here are some pictures:

 A540 running RISC OS 3.11 

A540 running RISC OS 3.11

 A540 running RISC OS 3.11. This A540 has been updated with the Universal Boot and is still a very servicable computer. In front is a BBC Archimedes keyboard, probably from an A310. 

 A540 logo

 A540 logo on front of system unit

 The Archimedes A540 logo on the from panel. 

  A540 back

A540 back view

 The back of the A540 showing the podules. This shows the podules and interface ports. At the top left is the Atomwide Ethernet IV card with an RJ45 socket, below is the Computer Concepts/Wild Vision Colour Card with the cable connecting its input to the RGB output. Below the Colour Card, you can see the 3 BNC connectors which are only on the A540 and R260. In the middle on top is the Acorn ACA31 SCSI card with the blockly external terminator (the 2 connected discs are internal), below the Acorn SCSI card is the Computer Concepts Scanlight podule. 

 A540 label on bottom of case 

A540 label on bottom of case

This is the label on the bottom of the A540 case. AKB50 is the product Code for an A540 which suggests that this is an authentic A540 which has not been asembled from spare or rescued parts! It may even have been number 35 rather than 1035 as relatively few were made.  

 A540 case open

 A540 with the top open

 The A540 with the top cover removed, this reveals a crowded interior. On the left is the power supply which is bigger than a standard Archimedes and contains 2 fans. In the centre at the front is a SCSI hard disc, the second disc is beneath the first one. The SCSI podule is behind the hard disc and hidden by the SCSI ribbon cable. The floppy disc is on the front right, behind it are the 3 RAM cards and the CPU card. In the middle just visible is the top of the backplane. At the back on the right is the Atomwide Ethernet IV podule. 

 A540 motherboard

 A540 motherboard

  The A540 with the podules, backplane, CPU and RAM cards removed to show the motherboard. At the top left is the floppy disc drive, with the 2 SCSI drives to it's right. Below the floppy disc drive are the sockets for th¤ÀÿÿJ

 A540 RAMcards

 A540 RAM cards

Three A540 RAMcards, each card has a MEMC1a and 4 MB of RAM. Together with the 4MB RAM and MEMC1a on the motherboard, this means you can have a 4MB, 8MB, 12MB or 16MB A540. These are all Acorn RAMcards, but Simtec also made RAM cards.  

  Acorn A540 ARM3 33MHz CPU

A540 CPU with FPA10

The 33MHz ARM3 CPU with FPA10 floating point accelerator installed. Acorn's Acorn A5000 and A540 FPA upgrade kit installation instructions   provides more information about installation and use of the FPA10. The FPA Support disc   is available in the Software section.  

 Acorn A540 backplane 

A540 backplane

A540 (No.2)

The second A540 is ex-Acorn, bought from an ex-employee a year or two ago. It is an interesting example because it is still running RISC OS 2.01 and has SJResearch Nexus Level 4 fileserver software installed. I have not yet tested this, mainly becaus I haven't yet build an Econet network to test it on. The CPU is a 26MHz ARM3. The Acorn AKA32 SCSI interface has 1 x 100MB hard disc attached. I have added a Computer Concepts Colour Card and Aleph1 386 PC card.
Here are some pictures:

 A540 running RISC OS 2.01 

A540 running RISC OS 2.01 with SJResearch Nexus Level4 fileserver software

  A540 ARM3 26MHz CPU

A540 26MHz ARM3 CPU

 The original 26MHz ARM3 CPU card which does not have a socket for the FPA10 floating point accelerator.


Serial No.27-ABK50-000103527-ABK50-0001057
Unique Indentityn/an/a
Motherboard part no.0186,000 Issue 10186,000 Issue 1
Motherboard serial no.FM-181-0000892FM-181-0000897
CPU ModelAcorn ARM3
CPU Clock33MHz26MHz
Floating Point
FPA10 26MHzn/a
Memory ControllerMEMC1a x4MEMC1a x4
Acorn RAMCard
0186,002 issue 1
Acorn 4Meg PCB
0286 Issue B
Memory Clock12MHz12MHz
Video ControlerVIDC1aVIDC1a
Floppy Disc DriveCitizen OSDC-65CCitizen OSDC-65C
Hard Disc ControllerST506/MFM
Hard Disc Drive540MB SCSI
Conner CP30100
Backplane ModelAcorn 4 slotAcorn 4 slot
Backplane part no.0186,001 Issue 10186,001 Issue 1
Podule 0Atomwide Ethernet IV
Podule 1Acorn AKA31 SCSI podule
0173,010 Issue 2
Acorn AKA32 SCSI podule Mk3
0173,080 Issue 1
Podule 2Wild Vision/
Computer Concepts 215B
Colour Card Issue 2.14
Wild Vision/
Computer Concepts 215B
Colour Card Issue 2.0
Podule 3Computer Concepts
Scanner I/F part no. 3172
Serialno. 0054
Aleph1 386 PC card

Other upgrades  
OS Date29-Sep-925-Jul-90
SICK v1.22
ARMSi v4.0