Sample Games

Extended Monitor

8K Super Invaders

Blank Tapes

I wrote several programs for the UK101 as well as typing in, modifying and converting many others. Most of them depend to some extent on the extra hardware that I added to my machine, but a few will work without it.

• Rather pedestrian calendar program CALENDAR. No prizes for finding Millennium Bugs in this one!
• Strange bit of code typed in from Personal Computer World, September 1980: BLOOBERS. The game was written by Richard Warner and was originally designed for the PET. I changed the screen address calculations and the keyboard polling so that it worked on the UK101.
• The UK101 didn't use the 6502 interrupt pins at all; that meant I could use one of them for a real-time clock RTCLOCK. You should be able to find a suitable 100Hz signal in the VDU divider chain.

I have three machines in all, my own highly modified one and another two that are nearly original. My machine is a fairly early model with mask ROMs, while the others are later and have EPROMs. Of those other two, one has now been fitted with a 6809 processor chip, as well as new ROMs to suit the 6809 CPU (the modifications are entirely reversible). The remaining machine is by far the most original and unmodified of the three, complete with cardboard box, and will be restored to operation in time for the 30th anniversary of the Compukit in 2009.

Looking at the three machines side-by-side, some minor differences become apparant. The most obvious is the use of EPROMs versus mask-programmed ROM chips, made by Synertec. But another difference, more subtle, is in the keytops on the keyboard. My own machine and the EPROM-based machine are identical, but the keyboard of the 1981 machine is different (see photo). The key for colon and asterisk is one of the more obvious ones, but in addition to that, the keys K, L, M and P on the older machines have symbols on them for use with SHIFT, that is, the square brackets and the backslash; the newer machine does not have them. The keyswitches underneath are exactly the same on all three machines.

Early machines were supplied with a bare mains transformer, and the builder was expected to connect it to the (240V) mains and to the UK101 with his own wiring. In later versions, the mains transformer is supplied in a moulded plastic case, and the wiring is ready-made. I wonder how many parents complained when their children were expected to wire up a mains transformer as part of the kit, as well as supplying their own connecting wire!

Along with the machines, I have several relevant magazines and much technical documentation. I have the official MOS Technology hardware manual for the "MCS6500 Microcomputer Family", Two early third-party manuals are "Programming the 6502" by Rodnay Zaks (Sybex, 1978-1983) and "6502 Assembly Language Programming" by Lance Leventhal (Osborne/McGraw Hill, 1979). Many later books were published specifically for 6502-based machines (usually the BBC Micro); I have "Creative Assembler" by Jonathan Griffiths (Penguin Books, 1984). I also have "Advanced 6502 Interfacing" by John M. Holland (Blacksburg, 1982) and "6502 Assembly Language Subroutines" by Lance Leventhal and Winthrop Saville (Osborne/McGraw Hill, 1982).

And, of course, there are the Practical Electronics magazines:

August 1979	Compukit UK101 Part 1	Dr. A.A.Berk
Sepember 1979	Compukit UK101 Part 2	Dr. A.A.Berk
October 1979	Compukit UK101 Part 3	Dr. A.A.Berk
November 1979	Compukit UK101 Part 4	Dr. A.A.Berk
December 1979	EPROM Programmer Part 1	Dr. A.A.Berk
January 1980	EPROM Programmer Part 2	Dr. A.A.Berk
February 1980	Acoustic Modem Part 1	Kenneth Amor
March 1980	Acoustic Modem Part 2	Kenneth Amor
	Compukit Update	Dr. A.A.Berk
June 1980	Compukit Update	Dr. A.A.Berk
November 1980	Speech Synthesis Part 1	Dr. A.A.Berk
	Resident Editor	Nigel Climpson
December 1980	Speech Synthesis Part 2	Dr. A.A.Berk
January 1981	Interfacing Compukit Part 1
February 1981	Interfacing Compukit Part 2
March 1981	Interfacing Compukit Part 3
April 1981	Interfacing Compukit Part 4
May 1981	Interfacing Compukit Part 5	D.E.Graham
	600 Baud Cassette Interface	P.Martin
June 1981	Interfacing Compukit Part 6
July 1981	Interfacing Compukit Part 7	D.E.Graham