[4] Fabricated using CMOS technology, the 65C12 used less power than the 6502 and offered somewhat better performance, reportedly "almost as fast" as the original 3 MHz 6502 second processor for the BBC Micro.

The cumulative effect of enabling shadow RAM and using the upper memory for workspace made almost 29 KB available for normal programs and was said to "transform the machine" from its predecessors.

In total, the updated OS, known as MOS 3.2 occupied 35 KB and incorporated features previously introduced in the Graphics Extension ROM for the BBC Micro, along with additional commands and system calls plus a variety of enhancements.

The inclusion of a real-time clock to keep the date and time was a notable built-in feature of the Master 128 and derived models, together with 50 bytes of battery-backed CMOS RAM to retain details of the machine's configuration while powered off.

[7] To hold the expanded OS and BASIC, the Master 128 was fitted with a ROM device having a capacity of one megabit, or 128 KB.

Alongside the OS and BASIC, a text editor suitable for writing programs was included, DFS and ADFS provided filing system support to access files stored on disk, the View and ViewSheet applications respectively offered word processing and spreadsheet functionality.

A terminal emulator was also included to support serial communications over the machine's RS423 port or the optional internal modem.

[7] The Master series largely carried forward many of the core architectural features of the earlier BBC Micro models.

This left an impression of the inside of the Master 128 being "another world" compared to the original BBC Micro, featuring fewer but larger chips.

One notable feature was the introduction of "relocatable" language (or application) ROM support, permitting appropriately written ROM-based software to automatically take advantage of a second processor, if fitted.

A disc interface was fitted, but the drives themselves were not included in the base product, these being offered by third parties and by Acorn as an official expansion.

It used the same main circuit board as the Master 128, but the components for missing interfaces were simply not fitted (though there was nothing stopping them being added later by someone with appropriate soldering skills).

[18] A product by Shibumi Software called Problem Solver aimed to address various compatibility issues related to the increased speed of the coprocessor relative to a traditional IBM PC, display and keyboard differences (also supporting the BBC Model B keyboard for users of that machine with the co-processor attached), the behaviour of "memory resident packages" such as Sidekick, and the behaviour of particular applications.

[20] The company also produced a selection of utilities for the Master 512,[21] including the Co-Processor Filing System (CPFS) which allowed the 512 KB of coprocessor memory to be used as a RAM disc by the computer when operating in its "native" BBC Micro mode.

It was to have an 8 MHz 32016 coprocessor with 32081 floating point processor and 512 KB of RAM, running the PANOS operating system.

Ultimately, Acorn dropped the Scientific due to unspecified technical problems with the co-processor, also indicating that 512 KB of RAM appeared to be insufficient for the target audience, whose applications tended to need 1 MB of RAM,[24] this already being provided by the upgraded 32016 Second Processor product known as the Cambridge Co-Processor.

[29] Indeed, one reviewer gave credit to Amstrad for having engineered the delivery of "an innovative, cheap machine for education" – the Compact – through robust competition with Acorn in the sector.

[32] The cartridge and cassette ports were removed as a space saving measure, and RS-232 hardware not populated on the circuit board as standard.

[33] However, the machine did include a 50-way expansion edge connector on the right side of the keyboard, that was similar to cartridge socket #3 on a Master 128.

[37] Acorn reportedly designed the Compact to appeal to home users and to primary education, with the single-plug power connection regarded as more convenient for setting up a machine that might be moved around in a school, and the choice of 3+1⁄2-inch discs using the ADFS format was regarded as conducive to "handling many small files" and "distinguishing between different topics or users on the same disc".

[40] Hence, it had no built-in real-time clock facility, although the time could be fetched via Econet where available, being applied to ADFS file timestamps.

The keyboard on the Compact was the first to move away from using the traditional "sprung-key" keyswitch design used by the rest of the BBC Micro family.

Little commercial software, beyond that included on the Welcome disk, was ever made available for the system, despite the claim by Acorn at the time that over 100 titles would be "set for distribution on 3.5in disc format for the Compact launch".

Software for the Compact was comparatively expensive (typically £20 for a game) due to the much lower demand for the 3+1⁄2-inch disk format (5+1⁄4-inch was the standard for the Master and earlier BBC Micro).