DISC SYSTEM WITH MOTHER

With the recent flood of disc interfaces for the Spectrum the Gordon Microframe has been largely overlooked. Although at £149.50 inclusive it is the most expensive it does have more potential than the others and can be built up into a very comprehensive system.

The Microframe is a disc-based motherboard system with a range of plug-in cards. A number of cards are under development at the moment, ranging from a simple Centronics interface through A to D, D to A, RS232 - for use with a modem - to I/O cards suitable for robotics.

The disc interface software is held on disc and booted into 16K of onboard RAM. That RAM is paged when a syntax error occurs. That means that not only is the DOS easily changeable but also that you can extend the Spectrum Basic; for example, the I/O boards can be driven using a Logo-like language.

As a disc system it is old fashioned in that it only uses single density. That, typically, gives 98K for storage on a 40 track, single-sided drive, and up to four drives can be used.

All the necessary commands are available: Load, Save and Verify for Basic, Code and Data plus Format and Erase. Open and Close are soon to be added. As it does not take up any of the Spectrum memory, even for a buffer, transferring software to disc is relatively easy. Gordon expects to release commercial software on the system soon.

The motherboard has been well thought out and it is quite straightforward to add your own boards.

The manual is comprehensive and gives details of all the relevant pin outs plus a description of what each one is used for. There are example programs, with some simple ones on disc, including one showing how to extend the Basic.

Although the board can be powered from the Spectrum Gordon does not recommend it as the tolerances are tight. It is designed to be powered from disc drives and, if those need power, Gordon supplies a supply for £63.25 inc.

The system is expensive, as you are paying for facilities that you are unlikely to use. In education, however, those facilities would be used to the full.

Gordon Microframe Ltd, 3 Callendar Road, Heathfield Industrial Estate, Ayr, Scotland KA8 9DJ. Tel: 0292-280467