Fifteen 80-Bus solutions

Gemini Microcomputers had been founded by John Marshall towards the end of 1980 after his previous company - [@Nascom/Lucas] - had called in the receivers.

Since its founding, Nascom had produced the [#Nascom 1] - which for a while was the UK's most popular kit computer - as well as the follow up, the [#Nascom 2].

Because of its popularity, a reasonable market had built up for expansion products - like video cards, memory boards, or disk controllers - which were targetting the [!Z80] processor and using the Nascom bus, known as NASBUS. 

However, the receiver appeared to have no interest in this bus as a "going concern" or in creating a standard with it, and so either Dave Hunt or Dave Greenhalgh[source: https://nascom.wordpress.com/history/] created a two-board system as a Nascom 2 contingency plan should the receiver fail to find a buyer for the company.

It was this, which became known as the Multiboard, that John Marshall took with him when he started Gemini, with it becoming the basis of Gemini's first micro - the Galaxy 1.

[picture: Nasbus_prac_may81.webp|Formerly known as: an advert for NASBUS-compatible products in "NASBUS News". Also shown as a complete Nascom 2-based system for £1,549 plus VAT, which is around [[1781|1981]] in [[now]] ]

Nascom was eventually sold to Lucas Logic - a division of the car-parts conglomerate - but the terms of the sale did not allow the use of the name Nascom anywhere, including as a prefix as in NASBUS.

As a result, Gemini re-released it with a new name - 80-Bus. At the same time it was tidied up and tweaked in what was apparently something of a bid to create a UK version of the S-100 standard.

One of the advantages of the "multiboard" arrangement was that it was possible to easily build a huge variety of custom configurations - a theme that the company made use of in its 1984 "[=gemini_percw_dec84|off the peg]" advert.

This particular advert shows four of the fifteen 8"-square boards which Gemini supplied at the time, including its GM811 CPU board, GM812 Intelligent Video Card (IVC) board and the GM829 floppy-disk controller (FDC) and SASI card - which together formed part of the standard Gemini configuration[source: https://glasstty.com/the-gemini-80-bus-saga-part-1/].

Also shown is the GM813 Z80A CPU card with 64K RAM on board.