INMC 80 News

Screen Control Unit Review

This is a review of the Screen Control Unit produced by:
R. W. Electronics, 27 The Vineries, Acocks Green, Birmingham, B27 6SB. The kit costs 27.00 inc. P&P and VAT.

This control unit provides 5 functions/​nbsp;:- reset, display on (normal), display off (blanked), white on black (normal), and black on white (reverse video). It is constructed on a single sided 8″ X 5.5″ fibreglass pcb that plugs into a NASBUS and has a wire connection to an existing Nascom IC socket.

The sample kit provided for review took under 2 hours to build on the well prepared board, the legends being very clear and informative. Over half an hour was spend in inserting the wire links required since the board is single sided.

No problems were encountered in building the kit. In fact this is one of the best presented kits our reviewer has seen. The only hiccup occured because the kit was first configured for a N1 (someone else can’t read simple instructions?) and could not be tested on the N2 available. The kit is not intended to be changable between N1 and N2 but with some careful soldering this was accomplished.

Anyone who is thinking of purchasing this kit should also acquire another edge connector socket since there is not one in the kit.

Testing of the unit presented no problems (it worked first time) although the suggested memory address for the unit (it uses a memory mapped port to control it) seemed a little strange. The handbook suggests using address D000H (selected by wire links on the board) but 0800H would seem a better alternative since this is not used by any known software and provides a record of the last code sent to the unit in the first location of screen RAM.

In summary, this would be a very good first project for someone who purchased a built Nascom and now wants to learn a little about assembling kits. The unit offers only VDU on – off, and screen inverse, and as such would seem to be somewhat overpriced. Perhaps a NASBUS socket could be provided in the price since it would appear that all other Nascom hardware suppliers provide a socket in with their kits. However, if you consider the time and effort involved in going it alone with a ‘DIY’ job, this unit would probably work out cheaper.