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C > COMPUKIT > UK-101     


Made in the UK by Compukit in New Barnet, North London, the UK-101 was originally a copy of the Ohio Scientific Superboard II. Two years and various legal battles later the UK-101 became, technically, behind its erstwhile rival.

You could buy the UK101 as a kit or as ready made for an extra fee. The kit came in a cardboard briefcase, in which there were anti-static tubes containing the 65+ ICs, a box of IC sockets, and bags containing passives (mainly 0.1uF ceramic decoupling capacitors) and keyboard bits (the keyboard switches were soldered directly to the PCB).

The UK101 came with a transformer in a plastic case, which was rectified and regulated down to +5, the regulator's heatsink was far too small and it would run very very hot, causing the RF modulator to drift channel. Many people relocated the regulator off-board onto a bigger heatsink to solve both problems.

It came with an A4-size book authored by Dr. A.A. Berk, covering assembly, trouble-shooting, and circuit diagrams with descriptions.

The UK101 was based around the 6502 processor. On top of ASCII characters, 128 graphic characters were available in ROM. The RAM memory was expandable from 4 KB to 8 KB on board, or 40 KB with an expansion board.

At the time, The UK101 was heavily supported by Watford Electronics in the UK, and by various electronics magazines who published circuits. There were many user groups and plenty of software available. It was thus possible to upgrade this machine beyond all recognision !
Several cases were also made and sold by a number of manufacturers.


Contributors: Paul Mansfield

John reports to us:
There were 3 monitor chips available, this being the 8k rom. The only one I can remember the name of was the Cegmon, the latest in the series.
The 40 pin expansion slot offered some inpressive (for the time) abilites. Mine had a sound card in it but I also saw systems with colour, hard drives and 5.25 floppy systems.

Some boards had links in them in place of the two sockets on your picture. These needed to be removed if you wanted to use the 40 pin expansion and a couple of 8T28s (buffer chips) put in their place. Other expansions I saw included a 'graphics' chip that could be switched in using software. A small pigiback board replaced the Normal character chip (which is the horizontal one in your picture) with the graphics rom and normal character rom slotted into it. This gave 256 additional characters, and since the replacement rom was an Eprom these new characters could be anything.

Programming was via Microsoft 8k Basic and involved a lot of Poke instructions to get it to do anything much. Overclocking was a breeze, but you had to get it right otherwise the screen divided into 4!

Martin Ward adds:
You could upgrade the graphics RAM by "piggkbacking" two new RAM chips on top of the existing chips, with one pin sticking out sideways which had a flying lead soldered to it. This gave you 48 characters x 32 lines.
The tape recorder could also be "overclocked" to 600 or even 1200 baud!
RAM cost about £10 per K (£5 per 1KB x 4bit chip).

Dick Greening reports:
An interesting story is that one of the BBC engineers rewrote the garbage collection routine (in the Microsoft Basic 4 Rom I thing it was,) only to find later that somehow Microsoft had incorporated his routine in their new version of Basic. He was able to prove it was his program as he had encrypted his name in the program! Sound a familiar story!

We need more info about this computer ! If you designed, used, or have more info about this system, please send us pictures or anything you might find useful.
Special thanks to Ivan Gleaves who donated us this computer !



The URL of the DIY UK-101 has changed quite a while ago. Here is the current one:

Wednesday 15th January 2014
Holger Palmroth (Germany)

Watford Electronics? That makes sense - as I rememeber buying and installing a new monitor ROM around 1981 is and I have the distinct memory that it was named WEMON. Needed a bit of board mod, trace cutting, extra wire. Provided full cursor control (you could print strings that would contain control characters to move your cursor around on the screen) and some other clever things that I can''t remember now.

Saturday 22nd November 2008
Stephen Burgoyne Coulson (UK)

Mine still works... A friend at the BBC made his work in colour... I wrote a space invaders game - four aliens... miss one and the 'bullet' got stuck in the code.... It crashed, list it and there was the bullet. (memory mapping the screen does that :>) BBC VT shift 1 was UK101 - Shift two was the Nascom machine I think. Shift one moved on to the BBC micro - then the Archimedes. Shift two went the IBM clone way. I was shift one - I loved my Risc OS - still use it whenever I can. Code is on my (aged) homepage.

Sunday 5th December 2004
Simon Anthony (UK)
Anthony family website


NAME  UK-101
TYPE  Home Computer
ORIGIN  United Kingdom
YEAR  1979
KEYBOARD  Full stroke 50 keys
CPU  6502
SPEED  1 MHz. (could be 'overclocked' at 2 MHz by modifying the clock divide circuit)
RAM  4 KB expandable to 8 KB on board
ROM  8 KB (Microsoft BASIC) + 2 KB monitor
TEXT MODES  16 to 48 chars. x 16 lines
GRAPHIC MODES  None, but 128 graphic characters
COLOrsc  Monochrome
SIZE / WEIGHT  unknown
I/O PORTS  Tape recorder (at 300 baud) and printer ports
POWER SUPPLY  External AC transformer. Power regulation on board
PERIPHERALS  Supports all Ohio Scientific expansions
PRICE  £249 in kit form



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