The Science of Cambridge MK14

The MK14 was one of the first home computers available to the general public in the UK. It was manufactured in about 1978 by Science of Cambridge, the company run by 'uncle' Clive Sinclair. It was sold as a kit for about £40, and used an SC/MP microprocessor. The kit came with a very detailed manual which you can view here. The basic RAM was 256 bytes expandable to 512 bytes (or more with extra decoding logic). The operating system was called SCIOS and was contained in 512 bytes of ROM (that's it on the background!) An optional RAM/IO chip provided a parallel I/O port and the optional VDU board allowed connection to a TV set. You had to be a bit of an electronics enthusiast to build an MK14, and afterwards, you needed the patience of a saint to learn how to program it. The machine was programmed by typing in the hexadecimal codes of the individual machine instructions. Contrast that with today's typical development methods. Some of the programs provided in the manual required hardware adjustments to be made. Once a program was in memory, it could be saved to cassette tape using an optional cassette interface board. This saved and loaded at about 4 bits per second, allowing you to write the entire RAM to tape in just under 10 minutes. I was able to adapt the circuit to work at 256 bits per second, although with some loss of reliability.

If you think that a computer with 1/4 of a kilobyte of memory is incapable of doing anything useful, think again. I used the MK14 as the heart of a home-brew electronic synthesizer setup.

Colin Phillips has made a reproduction MK14. Read about this amazing project here: MK14 V2.0