INMC 80 News


October–December 1981, Issue 5

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The Video Map published on page 52 of INMC80-4 was sent in by Mr W.R. Smith. Sorry we didn’t mention it at the time.

Would any Nascom fans in ABU DHABI care to phone ______ for exchange of ideas, programs etc? If so Ian Slater would like to hear from you.

Apologies for the length of time it sometimes takes to get articles that you submit into print. There are a variety of reasons for this, so if you sent something in some time ago, and haven’t seen it yet, don’t despair.

When is an Ad. not an Ad.? If you have some equipment to sell that you no longer use, then a small Ad. of 2 or 3 lines is free. If it is something that a private individual is selling for profit, e.g. copies of one of your programs, then there is a nominal charge of 5.00 for 7 or 8 lines. If you are a commercial organisation then it’s 100.00 per page, or proportional charge.

Finally, if there is anyone out there who would like to be of hardware &/or software assistance to fellow computer users, drop us a line and when we have a couple of dozen names and addresses we’ll print them.



by Paul Wilson

I have just purchased a “Gemini EPROM Programmer” from Bit’s & P.C.’s and thought you might like to know how I rate the kit.

Circuit board is superb quality and all hardware is included with the exception of connector plug(s) and a case. I.C’s are socketted and two Zero insertion force sockets are provided for EPROM. Why two? Well, the blank EPROM may be programmed from RAM data, or from a Master EPROM, providing quick copying facilities.

Documentation at first appears sketchy, but is adequate, construction is quite straight forward (provided that one is familiar with Tantalum capacitor polarities!) An ON/OFF switch is provided, also a 2708/2716 Selector switch. The omission of a Power-on LED indicator is, I think, a disadvantage, but is easily added. Connections to my Nascom 1 were straight forward, requiring DIL header plugs and ribbon cable plus 12V & −5V supplies. Testing is limited to checking the 25 volt supply generated on the board, and other chip supplies.

Software supplied comprised a tape (in N2 formt, so useless for me!) and an assembled listing with operating instructions. The program resides in memory from 1000 up, (less than 1K, so ROM’able!) and provides; checking for erased EPROM, verifying a Blown EPROM, and Blowing an EPROM from a Master or from an area of Memory. Since the Programmer interfaces to the PIO and this was to be the first time I had used this device (blush!) I was apprehensive – however, my first blank Prom was plugged in, software loaded and the unit switched on – the first check was to run the program to check for an erased PROM – all OK, so Blow EPROM from memory contents specified – the screen indicates Blowing and cycle No., after cycle zero an automatic verify occurs; all OK! Then disaster – There are 2 latch switches, push on and push off and I pushed the EPROM select switch instead of the power switch. This put 25 volts on my 2708 where it did not like it, and I suspect, fed back to my Nascom which filled the screen with garbage and would not reset. A power-down (and prayers) in seconds saved my Nascom and programmer, and even the 2708 checked OK, but runs too slow to use on the system (I have to copy it to RAM to use the programs on it). Subsequent EPROMs have copied perfectly and function OK in my system – I have fitted a blank plate over the EPROM select switch to prevent “accidental” operation (the switches are identical and side by side).

To summarise then the kit was easy to build, easy to connect and is easy to operate and good value for money – nuff said? As a confirmed idiot I can honestly say it is not quite idiot-proof. (By the way why are EPROM Erasers so expensive?)

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