Ward Electronics.  

Compukit UK101

• A single board computer using the 6502 microprocessor. 
• Sold as a kit of parts & accompanied by articles in "Practical Electronics" Magazine.
• Also sold fully built and tested.
• A UK version of the Ohio Scientific Superboard as sold originally in the USA.
• Originally had 4K of Static RAM, 8K Microsoft BASIC in 4 ROM's, 2k Monitor ROM.
• Expandable Via on board sockets.
• VDU with 1K of dedicated RAM
• 2K Graphics ROM
• Cassette interface (300 baud).
• ASCII Keyboard.
• UHF modulator.
• On board PSU  (transformer included in price but not fitted to board).
• Machine code monitor & I/O utilities in the monitor ROM.

The Compukit UK101 was my very first computer. Bought from CompShop in Barnet Hertfordshire for the grand sum of £205 + VAT as a Kit. This was the first reduction in price since its introduction were the price was £219 +  VAT for the kit, and £269 + VAT for the assembled unit.

On arriving home I was eager to get started on the build. I sorted all the components out; and set about building my first computer. Four hours latter I was ready to switch on. After, first checking for any mistakes that might have appeared, after soldering some 1300+ joints and checking that the power supply was delivering 5V, before fitting all the IC's into there sockets.

The moment of truth, all was looking well. The monitor screen was covered in random characters. But, on pressing the 2 reset buttons nothing further happened. On checking the board through once again I found that there was a short between 2 data pins on one of the 8 RAM chips (a pair of these chips gave you 1K of memory (at approximately £12.50 per K)), On clearing this short circuit, the computer burst into life. The screen displayed the information as in the screen shot below.

The UK101 was a computer which used totally standard components throughout and because it wasn't in a case (although a case was available) it allowed us experimenters to enhance/expand the machine. The first change most people made, involved moving the 5V regulator from the main PCB and fitting it to a larger heat sink off the PCB. One of the biggest draw backs with the machine, was the program/data storage facility. Using a standard portable mono cassette tape recorder it would take quite a few minutes to load programs of just a few K. Practical electronics published quite a few articles were by it was possible to upgrade the machine. One of which, included a very simple circuit to increase the I/O to tape from 300 baud to 1200 baud.

Some of the enhancements published for the UK101 included:-

• Higher speed tape I/O

• PIO using the 6821

• VIA using the 6522.

• A-D / D-A using ZN425.

• 2716 EPROM programmer.

• Programmable sound using the AY-3-8910.

• Medium resolution graphic cards.

Whilst all this was going on there were numerous other companies producing enhancements and newsletters. The UK101 was going from strength to strength. A few of the companies producing enhancements and newsletters include:-

• OSI/UK User Group.

• Premier Microsystems (Formally Premier Publications).

• Computer User Aids.

There was also Watford Electronics producing upgrades, but I don't think they produced a newsletter. Then Elektor Electronics magazine produced the Junior computer also based on the 6502. They had articles for the Junior which were easily connected to the expansion port of the UK101. I used there mother board, memory expansion card and floppy disc drive controller with my own  UK101. Although previously I used the Premier Microsystems disc controller on a friends UK101 and produced my own memory expansion card.

More to follow shortly.

Email: info@davidward.plus.com