Monday, 24 November 2014

Vintage Microprocessors

Whilst preparing some slides for a talk, I needed a picture of my first microprocessor which (I have to admit) was the General Instruments CP1600.

I was surprised to find the internet isn't exactly falling over itself with images of my "first date" - but there is an old example here in the junk box. So, by way of a public service, here's some vintage micro "porn"...

The nMOS CP1600 had an unusual 16-bit architecture, which it inherited from the PDP-11 minicomputer.

The spotty, teenage proto-m0xpd saved his pennies and purchased a CP1600 from Watford Electronics (it was far too exotic to be available from anywhere in Luton back in the 70s),

Here's Watford's logo and storefront...

I got my CP1600 to build a "computer" which was described in one of the magazines of the day - Practical Electronics or something similar. A quick internet search hasn't identified which magazine it was (if any readers remember - please let me know).

All I can remember of that computer is that I was too poor to be able to afford 16 switches to enter data - so I started off with an array of 16 pairs of 2mm sockets (one for logic "true" and one for logic "false") and 16 2mm plugs on short flying leads. The "switch array" was very much in the style of the PDP-11 (at least it would have been, if I had been able to afford switches).

Oh yes - one other thing - my computer had 256 words of memory. Those were the days.

The dalliance with the CP1600 was short-lived - I soon converted to the 6502 (the cheapskate's choice) here's a later example (evidently from RadioSpares)...

Interestingly, General Instruments "became" Microchip - I was to spend even more time playing with their products.

Now there are the sophisticated  distractions of Atmel and ARM etc - but I still enjoy looking at pictures of the simple, exciting processors of my youth - and I still have some of them here, hidden away, but "living with me". Don't tell the XYL!

...-.- de m0xpd

Update (21.3.15)

A little sniffing around on the www has unearthed the article which inspired my computer. It was indeed in Practical Electronics and was penned by one D S Coutts...

Coutts, D.S. (1979). MICROPROCESSOR EVALUATION SYSTEM. Practical Electronics, 15(5) p18

Coutts, D.S. (1979). MICROPROCESSOR EVALUATION SYSTEM - 2. Practical Electronics, 15(6) p42

Coutts, D.S. (1979). MICROPROCESSOR EVALUATION SYSTEM - 3. Practical Electronics, 15(7) p43

The first part of the series, from May 1979, is subtitled "Introduction to the CP1610 and its instruction set", which is interesting, given that I certainly built for the 1600!

The second part, from June, covers "Construction and testing", whilst July's final part is subtitled "Programming (Conclusion of series)".

It would be nice to see a copy of these articles again - anybody have old numbers of PE lurking on their bookshelves?

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