website/content/museum/sinclair-mk-14.md

---
title: Sinclair MK 14
categories:
- Computers
types:
- Home Computer
origins:
- United Kingdom
years:
- '1978'
cpus:
- National Semiconductor SC
params:
  name: MK 14
  image: /media/museum/photos/sinclair_mk14_system_1.jpg
  company: /companies/sinclair
  company_name: Sinclair
  specs:
  - label: NAME
    value: MK 14
  - label: MANUFACTURER
    value: Sinclair
  - label: TYPE
    value: Home Computer
  - label: ORIGIN
    value: United Kingdom
  - label: YEAR
    value: '1978'
  - label: END OF PRODUCTION
    value: Unknown
  - label: BUILT IN LANGUAGE
    value: Basic ROM monitor
  - label: KEYBOARD
    value: Sensitive and later mechanical hexadecimal 21key
  - label: CPU
    value: National Semiconductor SC/MP II
  - label: SPEED
    value: 4.4 MHz
  - label: CO-PROCESSOR
    value: Optional 8154 I/O RAM chip (not really a coprocessor..)
  - label: RAM
    value: 128 Bytes expandable to 640 bytes on board (not Kbytes!)
  - label: VRAM
    value: No video as standard
  - label: ROM
    value: 512 bytes, holds the monitor
  - label: TEXT MODES
    value: 1 line of 8 or 9 digits
  - label: GRAPHIC MODES
    value: None
  - label: COLORS
    value: Red!
  - label: SOUND
    value: None
  - label: SIZE / WEIGHT
    value: 11.5 (W) x 25.5 (H) cm
  - label: I/O PORTS
    value: I/O lines, external keyboard
  - label: BUILT IN MEDIA
    value: None
  - label: POWER SUPPLY
    value: External AC transformer. Built in 5v cc regulator
  - label: PERIPHERALS
    value: RAM and ROM cards, tape recorder card, video,...
  - label: PRICE
    value: £39.99
  tabs:
  - photos
  - adverts
  - links
  - videos
  photos:
  - title: FLAT KEYBOARD V.1
    subtitle: ''
    text: |-
      The first versions of the MK-14 were equipped with a cheap membrane keyboard. This version doesn't have neither the second 128-byte RAM chip nor the I/O chip.

      Thanks to Fabrice Siravo
    image: /media/museum/photos/sinclair_mk14_system_3.jpg
  - title: FLAT KEYBOARD V.2
    subtitle: ''
    text: |-
      Another flat keyboard version.

      Special thanks to **Chris Rowland** who donated us this boxed MK-14 version.
    image: /media/museum/photos/sinclair_mk14_system_s3.jpg
  - title: MECHANICAL KEYBOARD VERSION
    subtitle: ''
    text: Sinclair MK-14, the computing power on your hand!
    image: /media/museum/photos/sinclair_mk14_system_2.jpg
  - title: MECHANICAL KEYBOARD VERSION
    subtitle: ''
    text: www.homecomputermuseum.nl
    image: /media/museum/photos/sinclair_mk14_2%5B1%5D.jpg
  - title: REAR VIEW
    subtitle: ''
    text: ''
    image: /media/museum/photos/sinclair_mk14_rear_1.jpg
  - title: SOLDER SIDE
    subtitle: ''
    text: Notice the issue number IV
    image: /media/museum/photos/sinclair_mk14_solderside_1.jpg
  - title: KEYBOARD CLOSE-UP
    subtitle: ''
    text: |-
      The keyboard is composed of 16 hexadecimal keys and 4 function keys:\
      **\[TE\]** allows to enter a new hex value at the current address\
      **\[GO\]** to run a program in memory from the current address\
      **\[M\]** Increments the address counter and displays the next address location\
      **\[AB\]** allows to enter a new address value which becomes the current address
    image: /media/museum/photos/sinclair_mk14_keyboard_1.jpg
  - title: PROCESSOR
    subtitle: ''
    text: |-
      National Semiconductors introduced the SC/MP processor in April 1976. SC/MP means **S**mall **C**osteffective **M**icro **P**rocessor.\
      At the time, it was the cheapest 8-bit processor.
    image: /media/museum/photos/sinclair_mk14_processor_1.jpg
  - title: DISPLAY
    subtitle: ''
    text: The calculator display featured nine 7-segment digits. However, 8 of them were used on the MK-14
    image: /media/museum/photos/sinclair_mk14_display_1.jpg
  - title: RUNNING
    subtitle: ''
    text: ''
    image: /media/museum/photos/sinclair_mk14_display_s1.jpg
  - title: I/O CHIP
    subtitle: ''
    text: This I/O chip (NS 8154) allowed 16 additional I/O lines to be used. It also contained 128 bytes of RAM.
    image: /media/museum/photos/sinclair_mk14_iochip_1.jpg
  - title: TRAINING MANUAL
    subtitle: ''
    text: ''
    image: /media/museum/photos/sinclair_mk14_manual_s1.jpg
  - title: THE BOX
    subtitle: ''
    text: ''
    image: /media/museum/photos/sinclair_mk14_box_s1.jpg
  - title: SCHEMATIC DIAGRAM
    subtitle: ''
    text: |-
      Schematic diagram of the MK-14 Issue 2

      Thanks to **Graham Galbraith**
    image: /media/museum/photos/sinclair_mk14_diagram_s1.jpg
  adverts:
  - title: FRENCH ADVERT (1978)
    subtitle: ''
    text: ''
    image: /media/museum/pubs/sinclair_mk14_pub_1.jpg
  - title: UK ADVERT (FEB. 1980)
    subtitle: ''
    text: Thanks to David Wilson for this picture
    image: /media/museum/pubs/sinclair_mk14_uk-pub_1.jpg
  links:
  - title: MK14 v2.0 - How I recreated my first computer.
    url: http://mymk14.co.uk/
    text: Lot of content here !
  - title: The Sinclair / Science of Cambridge MK14 Web Site
    url: http://mymk14.co.uk/paulRobson/index.htm
    text: History, emulators, tech info, source code, ...
  - title: Wikipedia page
    url: http://en.wikipedia.org/wiki/MK14
    text: ''
  videos:
  - title: Science of Cambridge (Sinclair) Mk.14 Micro Computer presentation
    url: https://www.youtube.com/watch?v=ZCm9L94S-fY
    text: 'Length: 5m 43s'
  comments:
  - author: Michael Butler (England)
    date: Wednesday 14th May 2014
    text: |-
      I always wanted one of these when I started looking at Practical Wireless, aged twelve or so...even one hundred pounds was too much - a LOT of money nack then, I got fifty pence per week pocket money, lol.

      Now I''m all Grown Up and Professional, I think it''s time I got one of these - great toy, plus good tool for Education too.

      I have quite a few legacy bits and piieces...SUN SPACstation 2, VT220, 500MB dead heavy hard drive...primitive,, but so much better build qulaity than today. I''m hoping to make someswaps here, and finally get my own Mk 14.
  - author: doug rice (UK)
    date: Wednesday 6th March 2013
    text: |-
      I used to have an MK14. Last summer I put a tool chain together using Paul Robson''s simulator and an assembler.

      Assemble MK14 code and start the simulator with the code loaded.
  - author: Neil Barnes (UK)
    date: Friday 13rd July 2012
    text: |-
      The first computer I bought$ I''d just started work and couldn''t run to a Nascom... like all things Sinclair I believe I had to resort to legal threats to get the thing delivered. But I learned an awful lot from that thing - including designing a video card from scratch, after a lot of false starts, and a tape interface.

      One odd memory was standing in Technomatic in London (Edgware Road?) for a couple of memory chips for it when a chap slammed the door of the shop open, rode in on a unicycle, spun around a couple times, yelled ''B\*\*\*\*\* me!'' and rode out again...

      The MK14 is still on my desk at work.
  - author: D.A.T (Alex) (Greece)
    date: Thursday 21st June 2012
    text: '...sorry forgot the link!'
  - author: D.A.T (Alex) (Greece)
    date: Thursday 21st June 2012
    text: Sinclair MK-14 Replica. Trying to revive the original pcb (as close to original as possible!) Sorry only in Greeks but online translation will do the trick!
  - author: Richard (Cheshire (UK))
    date: Wednesday 6th October 2010
    text: |-
      I still have mine :) baught when I was 12...still have the manual too...

      Before long I was modifying the logic, reducing power consumption $ adding my own chips glued upside down in the middle of the board. This tidied up the somewhat messy memory map ready for a memory expansion board that I never completed (Ram $ Rom). I also replaced the horrible membrane keyboard with better keyswitches $ added a full length heatsink to the overheating regulator.

      I then completed a speech board, amazing my friends by making the MK14 burp $ laugh etc.

      No-one pointed out that this was not actually a ''Sinclair'' product ??, rather the even older "Science Of Cambridge", headed by Clive himself.

      Regards
  - author: Bob Garland (UK)
    date: Friday 4th June 2010
    text: I still have the muscle reflex in my arm from pressing TERM-MEM-TERM after every byte of Hex! I can remember entering the incredibly long Moonlander program of 100 bytes+ of code to play what would now be considered an incredibly tedious game.
  - author: Graham Galbraith (UK)
    date: Monday 29th January 2007
    text: I still have mine in working order, (2006). Mine is an earlier one than the one pictured and so had the much-reviled membrane keypad which most owners replaced within days. However, I can not stress enough how valuable this machine was - it made it possible for me to buy and learn about microprocessor technology when other machines costing hundreds of GPB were way out of my reach. What it taught me then, I still use now.
  oc_id: 961
  source:
    url: https://web.archive.org/web/20230224111139/http://www.old-computers.com/museum/computer.asp?c=961
    date: '2023-02-24'
---

The MK-14 was the first computer made by the Sinclair company (at the time called **Science of Cambridge** because the Sinclair name was used by another company).

The MK-14 was a training board sold in kit form for £39.95 and featuring a National Semiconductor SC/MP 8-bit processor, 256 bytes of RAM, 512 bytes of ROM holding a monitor, calculator keyboard and display, and some I/O ports.

In fact, Clive Sinclair was not very enthusiastic about a personal computer project. The MK-14 project was thus managed by **Chris Curry** and produced by National Semiconductor. As the system was five times cheaper than its closest competitor, the Compukit UK-101, about 20,000 MK-14 boards were sold in the U.K.

Chris Curry, who believed much more than Clive Sinclair in the future of such computers, left the company in 1978, founded **Acorn Computers** with **Herman Hauser** and built its fist computer kit, the **System 1**. A few months later, Clive Sinclair decided that computers were a good way to raise money and started a new project: a complete computer for less than £100.

Meantime, the MK-14 grew into a modular system and several additional cards allowed expansion of the system: cassette interface, text and graphics video module and Eprom programmer. 128 and 256 bytes RAM expansion chips could also be added up to a total of 640 bytes. Yes...640 BYTES...

The version pictured here is an issue 4 with a better mechanical keyboard than the 'sensitive' one of the earlier versions, as well as optional RAM and I/O chips. At least 5 issues were sold. The issue 5 featured additional I/O ports.

If the MK-14 had not been launched, Clive Sinclair probably wouldn't have thought of his ZX-80 so soon, and the global personal computer scene would have been very different.

---

**David Rayner** adds:\
The Keyboard was unreliable I bought a separate keyboard. There was no storage so every program had to typed in machine code every time. (I never had the tape interface).\
The first test program was jmp 0000 (3 bytes). There was a shoot the duck game (a character flying acroos the calculator style display). By connecting a speaker you play "music". It was actually quite fun.

**Mark Dodd** reports to us:\
We used these things with a ROM burner in an Australian college for our Microprocessor training.\
The smarter ones in the classes wrote programs that rewrote themselves as they went.