ZX Spectrum Games

ZX Spectrum Games

2 Oct 2013

Spectrum Games - Programmer Interview - Kevin Allison

Kevin Allison
Kevin Allison worked on both the ZX81 and ZX Spectrum in the early 1980's as a games programmer before moving on to other areas.

His most recognisable title for the Speccy was Spectipede released by R&R Software and later Mastertronic.

I managed to get in touch with Kevin via YouTube and he kindly agreed to do this interview with me about his days as a games maker during the 8-bit era.

1: Hello Kevin. How did you get into games programming?
My interest in home computing was first piqued when I went to a party and they had a early model Commodore Pet running, with Space Invaders on, and from there I never looked back. Not long thereafter, I moved into the IT industry (in 1980) as a System Tester for a profession (in the days when a mainframe filled a whole very large room) and I soon bought a ZX81 as a kit and my interest was taken from that time. My first and only ZX81 program was Bomber, launched through R&R Software -

Buying the ZX81 as a kit was worth it from the point of view it gave me a great understanding of how the hardware linked together, something I've never forgotten and still use that knowledge today when upgrading/modifying my PC.

2: How did creating Spectipede for R&R Software come about?
I was an avid arcade game player at the time when the Spectrum came out, having a small arcade near the office where I worked. Pacman and Centipede were my two favourite games so I set myself the challenge to re-create Centipede on the Spectrum written entirely in machine code. I learnt machine code programming courtesy of the excellent book - Z80 and 8080 Assembly Language Programming by Kathe Spracklen (I still have the book)

I first of all wrote my own machine code driven real time two pass assembler (KAOS) which I initially hand crafted using REMs to Poke Z80 machine code and then used the early development assembler to further refine the assembler itself and also then used KAOS to build Spectipede.

3: How long did it take to complete the coding of the game?
I can't remember now but probably around 3 or 4 months to fully finish, refine and debug.

4: As far as I can tell, Spectipede is your only ZX Spectrum title. If this is the case can you tell me why?
Later on I also wrote "Ice Attack" in machine code as a spectrum version of the Pengo arcade game. I chose not to market KAOS nor Ice Attack for various reasons, for KAOS it was probably because the market already had a few two pass assemblers in play and I had missed the boat by the time it was fully finished, and it was also a bit more of a product for a niche market rather than mass market - therefore in practical terms no great fortunes to be made !

For Ice Attack, it was finished but I couldn't get a royalty deal I was happy with so it stayed in the box and there it will stay (not sure whether I still have the master tape anyway). PPS - "KAOS" = "Kevin's Assembler and Operating System" (As well as being a two pass assembler, it also took over control (using non maskable interrupts) of the Spectrum operating system and command line prompt to provide for real time input and validation of Rem strings containing only valid Assembly language commands only (table driven).

5: What did you move onto after the game was finished?
See Q4 above. I've done things like build PCs from scratch using my knowledge from building the Spectrum, buying just the PC components but have not not ventured back into software development.

6: With the retro-gaming scene booming would you ever consider creating another ZX Spectrum game?
No, too time consuming for me

7: Is there any chance of a 'Spectipede' 2013?
As Q6

8: What did you like about programming on the Spectrum?
Key point for me and friends in buying the spectrum was the move to colour and more memory !! (my first spectrum arrived faulty and had to be replaced straight away) For programming, key like was that the Spectrum used the Z80 processor which used interrupts easily accessible by the user including NMI and it came with a very rich machine code language, making it quite easy for complex program development.

9: Conversely, what did you not like programming on the Spectrum?
Nothing particular to dislike (other than the slow rubber keyboard !)

10: Which developers or companies impressed you most at the time?
No companies/developers in particular as I recall but my two favourite games were probably Manic Miner and Jet Set Willy.

11: Can you tell us what you are up to nowadays?
I am now retired from work and enjoy travel. Life seems to get more hectic when you retire, and free time less, but I still find time to keep up with modern technology !!! I now have fibre optic broadband with a home wifi network with PC, laptop, Nexus 7 etc all inter-connected - things we take for granted now but could only dream about back in the ZX81 days.

It is difficult to believe how far technology has advanced since the likes of the Pet and the ZX80 (if you remember much that far back - don't know how old you are ?)

I worked in IT from 1980 onwards and interesting to see that the modern handheld stuff now is way more powerful than some of the mainframe stuff we had all those years ago occupying whole rooms.

Once again many thanks to Kevin for taking the time to talk to me.
Cheers folks and I hope you enjoyed it!

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