BBC Micro expansion unit

[2] The Bitstik CAD system,[3] originally developed by Robocom for the Apple II,[4] was offered as an accessory for the 6502 Second Processor, also requiring dual 80-track floppy drives.

The Bitstik system itself was introduced with a price of around £375, which combined with floppy drives estimated at £500, the second processor at £199, the cost of the BBC Micro itself at £399, and the price of a colour monitor (Acorn recommending their own RGB monitor[3]: 2 ), the total investment was estimated to be between £1500 and £2000 depending on any particular customer's existing equipment and preferences.

[6] The original Bitstik product had been introduced for the 64 KB Apple II Plus in 1982 at a price of £275 for the device and software itself, with a complete system costing around £2000.

In a review published in late 1982, the solution was regarded as "the most powerful drawing system available in Britain today for use on small computers".

It required the floppy disc upgrade and, being aimed at business, enabled the BBC system to run CP/M programs.

[5] The product was launched in mid-1984 at a price of £299 and included an estimated £3000 worth of bundled software that included the CP/M 2.2 operating system itself (with GSX graphics), CIS Cobol and utilities from Microfocus, the Memo Plan, Graph Plan and File Plan office applications from Chang Laboratories, the Accountant and Nucleus packages from Compact Accounting Services, and two BASIC implementations: Z80 BBC BASIC and Mallard Professional BASIC.

[9] Despite "a policy of continuous improvement", Acorn apparently abandoned plans to update the software bundle in mid-1986 due to a review of the CP/M market.

[10] Other suppliers continued to support the Z80, delivering Z80 second processor hardware and software bundles, such as the Task-Master which combined an externally connected second processor, compatible with the BBC Model B, B+ and Master, and a suite of software including a CP/M 2.2-compatible operating system known as ZCPR3 and Borland's Turbo Pascal plus other development tools.

[11] Originally referred to as the Gluon, a National Semiconductor 32016 second processor solution was apparently planned for the BBC Micro and for other 8-bit microcomputers, with the BBC Micro version employing the Tube interface and offering a quarter of a megabyte of RAM, whereas the "Universal Gluon" would be connected to a microcomputer acting as a terminal using a serial or parallel interface, offer up to 1 MB of RAM, up to 5 MB of hard disk storage, and either a minimal operating system or Unix.

[12] Subsequent news of the second processor indicated the renaming of the product, dropping the Gluon name, the use of Acorn's own Panos operating system instead of Xenix, with availability in 1985.

Various programming languages are available including C, FORTRAN, Lisp, and Pascal, in addition to a version of BBC BASIC.

Originally, Acorn had apparently sought to use CPUs rated for 10 MHz, but seemed to have settled for available parts as the different products were introduced.

[21] Several other second processor solutions were produced by third-party suppliers, typically employing a different style of casing than the standard expansion unit profile, with some using the 1 MHz bus instead of the Tube connector, and with others merely providing a conventional serial link.

Performance concerns associated with the 68008, due to experiences with the Sinclair QL, were alleviated through the presence of "plenty of sub processors", these utilised for managing peripherals including control of floppy and SASI-compatible hard drives, coupled with the use of a relatively fast 8 MHz CPU.

[39] The initial software to use the adapter was quite basic but the BBC decided to rewrite it[citation needed] and produced the Advanced Teletext System in conjunction with GIS.

The new ROM software added several features including support for the new Fastext system, which introduced the four coloured buttons subsequently found almost ubiquitously on European remote controls, including the "red button" which remains a feature of digital television broadcasting.

The Econet bridge is unique among the cheese wedge expansions, in that it is a stand-alone device that does not require a BBC computer to operate.