The Gemini 80-Bus Saga - Part 2

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Revision as of 19:43, 5 December 2019 by John (talk | contribs) (A Look Inside)
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Thanks to the generosity of Charles Obrien of Hunmanby (formally Blunsdon Swindon), I am now the proud owner of a Gemini GM916 Galaxy MFB. The unit includes 5.25", 8" and 3.5" disk drives and a Winchester disk. The machine had been used by Charles when he ran a consultancy business called Obsys.

The Multi Format Bios allows CP/M to be configured for hundreds of floppy disk formats from many manufacturers and is ideally suited to converting from one format to another. The machine was purchased from a company called Timeclaim Ltd located in Woodbridge, Suffolk who also provided service, support and updates. The documentation that came with the machine was mostly produced by Timeclaim Ltd.

A Look Inside

Before switching the thing on, I thought it would be wise to open her up, take stock and make a few basic checks.

The machine consists of the following;

  • GM813 CPU and Memory board
  • GM832 SVC Video Controller
  • GM849 Floppy/SASI Controller (Modified for MFB)
  • An 8 inch double sided drive
  • Teac FD55 48tpi 5.25 inch Drive
  • Teac FD55 96tpi 5.25 inch Drive
  • 3.5 inch drive
  • Rodime 201 5Mb Winchester Disk
  • GMnnn Keyboard
  • GMnnn Monitor

The external condition of the computer is typical of a metal cased unit that has been stored in a loft for 30 years or so, however, looking at the inside you could be forgiven for thinking it had just been supplied from the factory.

Turning on suggested that a few sanity checks might have been wise as there was a distinct smell of burning. Time to strip, clean and test.

The Multi-Format Bios

The Multi Format BIOS (MFB) is an extension of the normal Gemini bios and supports all the usual features such as disk error trapping, screen edit, screen dump etc. Howeve the MFB will support a variety of disk formats simultaneously.

To support the MFB, five programs and a data file are supplied.


Details of these programs and their use are shown in their respective manuals which will soon be available to download the Gemini 80-Bus Resource page.

... more to come soon...