The MK14 (Microcomputer Kit 14) was a computer kit sold by Science of Cambridge of the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, first introduced in 1977 for £39.95. The price was very low for a complete computer system at the time, and Science of Cambridge eventually sold over fifteen thousand kits.

History

In 1977, Ian Williamson approached

Clive Sinclair Sir Clive Marles Sinclair (30 July 1940 – 16 September 2021) was an English entrepreneur and inventor, best known for being a pioneer in the computing industry, and also as the founder of several companies that developed consumer electronics ...

and

Chris Curry Christopher Curry (born 28 January 1946 in Cambridge) is the co-founder of Acorn Computers, with Hermann Hauser and Andy Hopper. He became a millionaire as a result of Acorn's success. In his early career days, he worked at Pye, Royal Radar ...

with a computer design based around the

National Semiconductor National Semiconductor was an American semiconductor manufacturer which specialized in analog devices and subsystems, formerly with headquarters in Santa Clara, California. The company produced power management integrated circuits, display drive ...

SC/MP National Semiconductor's INS8060, or SC/MP (pronounced ''scamp'') for Simple Cost-effective Micro Processor, is an early 8-bit microprocessor which became available in April 1976. A unique feature of the SC/MP is a daisy-chained control pin that al ...

processor. Sinclair and Curry both liked the idea and saw the potential of making a low cost microprocessor system available to the hobbyist market. Initially it was planned to market a kit based on the Williamson design. However, after National Semiconductor had been contacted regarding a bulk purchase of the

processor Sinclair and Curry decided to use the chip manufacturer's own design. This design used all National Semiconductor chips and the company allowed the use of its designs, the SC/MP Introkit and Keyboard Kit, for free. The National Semiconductor SCMPKB Monitor code was included. To keep costs low a membrane keypad was used. The size of the initial batch was two thousand. The company sold between fifteen and fifty thousand in total.

Specification

The computer is based around

CPU (INS8060) and shipped with 256

byte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...

s of

random access memory Random-access memory (RAM; ) is a form of computer memory that can be read and changed in any order, typically used to store working Data (computing), data and machine code. A Random access, random-access memory device allows data items to b ...

(RAM) and 512 bytes of

read only memory Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing soft ...

(ROM) as standard. It used an eight or nine red

light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (cor ...

(LED) seven

segment display A display device is an output device for presentation of information in visual or tactile form (the latter used for example in tactile electronic displays for blind people). When the input information that is supplied has an electrical signal the ...

, there was also optional VDU supporting 32×16 text or 64×64 graphics. Input and output was a 20-key

keyboard Keyboard may refer to: Text input * Keyboard, part of a typewriter * Computer keyboard ** Keyboard layout, the software control of computer keyboards and their mapping ** Keyboard technology, computer keyboard hardware and firmware Music * Musi ...

and reset switch. Cassette-based and PROM storage were optional extras; a sound card was not included but a design for one was provided. The on-board RAM could be increased in two ways; by the addition of an INS8154N RAM/IO chip providing an additional 128 bytes of RAM along with 16 I/O lines, and also a further 256 bytes by adding two 256 × 4 bit RAM chips giving a maximum of 640 bytes on board. These memory spaces were not contiguous in the memory map. It was possible to connect off-board RAM giving a 2170 bytes total. The MK14 could address up to 64 KB of memory space by adding a few chips (the NADS address strobe indicated when the most significant four bits of address were available to be captured by an external latch); many pioneering homebrew computer magazines such as ''

Personal Computer World ''Personal Computer World'' (''PCW'') (February 1978 - June 2009) was the first British computer magazine. Although for at least the last decade it contained a high proportion of Windows PC content (reflecting the state of the IT field), the mag ...

'', and ''

Practical Electronics ''Practical Electronics'' (previously known as ''Everyday Practical Electronics'') is a UK-published magazine that is available in print or downloadable format. Publication history ''Practical Electronics'' was founded in 1964 by IPC Magazines ...

'' carried details of user modifications.

History

Specification

See also

Notes

External links