Andreas has gone largely unreknowned for his first and most famous Gameboy emulator, one of the first console emulators on the Acorn (and indeed one of the first Gameboy emulators anywhere) which he released anonymously under the pseudonym of Purple Monchichi. He later developed another Z80 based emulator, the CPC emulator which is widely considered the best CPC emulator on the Acorn. Note, some of Andreas' replies have been amended by myself at his request to improve the (already very good) English.
When did you start work on the gameboy emulator?
I don't remember exactly, but it was someday between the day I got my Acorn (about August '94) and end of '94. After years of experience on my old and nice Amstrad CPC I learned BBC BASIC and Assembler very fast (ARM assembler is much easier than Z80). I knew the capabilities of the gameboy (same speed as the CPC and Z80-like CPU), so I thought that it might be a great idea to play gameboy games on our machine. At this time I didn't know of any other gameboy emulator on any other system.
What gave you the idea to start working on the gameboy emulator?
I always want to program something which is some kind of a challenge for me, something really new. I'm also familiar with the Z80 like instruction set of the gameboy and somehow got the information about the gameboy necessary to write such an emulator. So, I thought, "let's do it"! Another strong point was that I was able to re-use the code and knowledge about emulation for my second project, the CPC emulator.
Where did you get the technical information write the emulator?
Funny, this is the part i don't remember :)))
What was the most enjoyable part of writing your emulator?
You have lots of work with the screen/display emulation. So you immediately see the results when implementing new parts. It's much more fun than writing 'invisible parts' like the CPU emulation. Also seeing the first game doing something on the screen was pretty fun.
Why did you release the emulator anonymously?
At the time it was not self evident having all the emulators around like nowadays, and I was worried about the legality of such an emulator.
Where does the name purple monchichi come from?
Well, do you know the role playing online (BBS-)game L.O.R.D (Legend of the Red Dragon)? It's a purely text based game which I was playing for about half a year (much fun!). It's a game were you can go into the forest to kick some elves' ass and earn skills and money for it and then buy larger weapons and challenge some other online players to earn again more money and skills. One of those 'chop me into pieces to get some money'-enemies inside the forest was called Purple Monchichi, that's all...
Why did you stop developing the emulator?
In my opinion it is good enough, no need for further development. If it were shareware I would have to care about the users, but it's free and i'm the only user I care about :) Further enhancements would just eat up my small sparetime.
What do you think of Paul Clifford's enhancements to your code?
Basically I like a multitasking emulator, but there were some missing features (no single tasking, didn't accept non-filetyped files) and some games which dosn't run on his hack, so that I never used his version.
What's your favourite gameboy game?
One aim always was to get the best action game onto my Acorn: Contra! The other favorite game is of course Tetris. Other good games are Batman 2, Ninja Gaiden, Probotector and Mario Land.
Do you use any other emulators?
Yes, i like console emulators like the PC Engine emulator by Paul Clifford. But maybe 'do you use' is the wrong question if i think about the 8-bit emulation. It's more like going into the past to see the good old cr*p. I would also use a SNES emulator if there would be a fast one...
Are you working on any other emulators?
I was working on a native SNES emulator (currently 25 to 40 fps without frameskip). Maybe I will continue on that project, with the public SNES9X sources available now. The CPC emulation is also not as perfect as i want. As always, the problem is my lack of time...
Anything you'd like to say?
Yes, I wanna greet my lovely girlfriend Gabi and what I wanted to say to the rest of the world is: 'Magic the Gathering' rocks! Get infected!