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My first computer
1978 was a year that was to change my hobby and interests for the future. That was year I bought my first computer magazine and it just happened to be Volume 1, Number 1 of Personal Computer World (PCW). I still have the bound copies of the first year's magazine, and as I look back through them, the developments that have subsequently taken place never ceases to amaze me. At that time the Science of Cambridge MK14 at just £39.95 was the affordable development kit with led display, Hexadecimal Keypad and 256 bytes of memory, whereas the NASCOM 1 with its 2K 8 static Ram and it's TV monitor o/p was strictly for the men at £197.50 For me, whose hobby to that date had been strictly amateur radio, the prospect of being able to build and control my own microprocessor system was very attractive, especially as PCW featured full details of such a project in their first issue. It was the 77-68, The Mighty Micromite, written by Tim Moore. This project had all the backing anybody could ask for, it was supported by the British Amateur Computer Club, and all the components were readily available from Newbear Computing Store, an offshoot of Newbury Labs. It was possible to buy the printed circuit board, a bag of components, and the handbook either collectively in what were called Bear Bags, or individually as and when required. I recall purchasing the circuit board and manual, and nipping along to buy the components when I could afford them. By the time I had built a power supply and constructed the mighty Micromite, I reckon it had cost me about £60 and for that I could enter the machine code instructions for the Motorola 6800, the CPU at the heart of this great machine. Data was entered in binary on the eight switches fitted for this purpose, and at each address which was also selected in binary on another set of switches. With its 256 bytes of Ram and it's 8 leds one could spend several days programming the CPU to flash leds like a Christmas tree, or by attaching an audio amplifier across one of the leds and switching it on and off at an audible frequency, play several tunes which would appear regularly in the 77-68 User Group Newsletter. What an idea, constructing a computer together like one big family sharing our problems as we all strived to build the same project. It didn't take long for that idea to bite the dust. The next step was to develop an operating system, and Newbear offered two choices - an EPROM based OS, or a bootstrap loader to load in an operating system from tape, one which could be easily modified and upgraded, but which had to be patiently loaded with the aid of a domestic tape recorder releasing its data at a rate of 1200 baud, every time the power was switched on. I chose the former, having access to an EPROM programmer at the time. By the time issue 3 of the newsletter appeared, it was becoming clear that everyone had different ideas on how their computer should develop and no longer were we all building the same project. EPROM, vdu, static and dynamic Ram boards appeared and as the projects diversified, the newsletter got thinner until the group eventually closed down along with the supplier. Undaunted I pressed on with my little project which now included an operating system with a fast decreasing 256 bytes of memory and which could accept keyboard commands but without the means to see what I was typing in, A vdu board was next, followed by 4K of static Ram then 32K of dynamic Ram and my own operating system which proudly pronounced "Hi Fred" every time I switched it on. An EPROM board finally introduced me to the world of BASIC programming. Printers were a luxury and I had to write machine code program to convert ASCII to BAUDOT 5-bit code, for my poor man's printer - an ex-government teleprinter. It was about this time, having spent about £200 over the years, that Clive Sinclair introduced his ZX80 at about £49 and it had graphics too! So it was that my machine came to the end of its useful life, and one day after a power surge crashed my programming session for the fourth time that night, that I succumbed to buying the latest black box which featured the same family of microprocessor - the Dragon 32K. Suddenly I became aware that I had no idea what made this box tick. If things went wrong, I could no longer tweak the operating system. It was a move I could not reverse, but it was a dark day when I gave up my baby for a plastic box! It was this interest in computing that was to make me aware of something called The Internet, but which was totally confusing without access to it. And so it was, around 1994, that I went to the local university (UCLAN) and did an introductory course. It was there that I decided to have a go at building a web site, and you can read more about that here. Fred |
