Editing Acorn Archimedes A540 (section)

== Hardware Specifications ==

=== Processor ===
The A540 featured an ARM3 processor on a replaceable CPU card. Initial models shipped with processors running at 25-26 MHz, though variants existed running at 30 MHz and 33 MHz. The 26 MHz version used a 52 MHz oscillator, while some machines used 60 MHz oscillators for 30 MHz operation. The ARM3 included 4 KB of cache memory, providing substantial performance improvements over ARM2-based models.

The CPU card could accommodate an FPA10 (Floating Point Accelerator), with FPA11 also being compatible with later variants. The 33 MHz ARM3 CPU with FPA10 combination represented the highest performance configuration available. The ceramic ARM3 processors used in some machines could be overclocked, with reports of stable operation at up to 40+ MHz.

=== Memory System ===
The A540 had 4 MB RAM by default but could be expanded to 16 MB with additional RAM cards, each with its own 4 MB RAM and MEMC1a memory controller. This unique multi-MEMC configuration allowed the A540 to exceed the 4 MB limitation of single-MEMC systems. 

The memory expansion was achieved through up to three additional RAM cards, giving possible configurations of 4 MB, 8 MB, 12 MB, or 16 MB total. Both Acorn and third-party manufacturers like Simtec produced RAM cards for the system. The memory cards were noted to be somewhat temperamental and liable to become dislodged if the machine wasn't used for extended periods.

=== Storage ===
Unlike the rest of the Archimedes range, the A540 had a SCSI interface as standard, specifically using an NCR 53C90 or 53C90A controller. The machine shipped with a 100 MB SCSI hard disc, with the Acorn AKA31 or AKA32 SCSI interface providing both internal and external SCSI connectivity. The system retained the standard 800 KB double-density 3.5" floppy drive used across the Archimedes range.

=== Video System ===
The A540 used the VIDC1a (Video Controller) chip and included three BNC connectors unique to the A540 and R260 models. The system supported various display modes with resolutions up to 1152×896 pixels and could display 256 colors from a palette of 4096. The memory access frequency was raised to 12 MHz in the A540, compared to 8 MHz in earlier models, providing enhanced system performance.

=== Power Supply and Cooling ===
The A540 featured a larger power supply than standard Archimedes machines, containing two fans for cooling. The system was noted to generate considerable heat, particularly with fully loaded configurations, and the memory cards were susceptible to heat-related issues.

=== Expansion ===
The machine provided four podule (expansion card) slots, with all four remaining available for expansion since SCSI was integrated on the motherboard. The backplane supported various expansion cards including:
* Atomwide Ethernet IV cards for networking
* Computer Concepts Colour Card Gold for enhanced graphics
* Aleph1 386 PC emulation cards
* ScanLight podules for scanning
* MIDI interfaces