I was very lucky as a child, my interests where always out there and they always prompted me to research and think out of the box. I was never very good at school but I am very good at learning what I’m interested in. As a result, I became a self taught engineer working in the audio and video industry.
My parents always supported my science and electronics interests by providing me with anything I needed to experiment and learn. My mother will bring all types of broken appliances found in other people’s trash for me to analyze. My dad was kind enough to supply me with a keyboard for my musical inclinations and a computer for my programming interests. Little did I know that the computer my dad got me was the first to include in its guts the must advanced analog sound chip at the time, the MOS Technology 6581/8580 SID (Sound Interface Device) chip.
So a couple of years ago I decided to get a bunch of these little computers and harvest the SIDs inside of them. That’s when the fever kicked in, back to the C-64 docs and the SID specs. I wrote various programs that took advantage of the SID chip, it is always great to go back to program this little machine in assembly, fun, fun, fun. That is all good for fun and programming but the more I listen to it, the more I thought that the quality of the sound achieved was far from being a clean professional synthesizer. The Commodore 64 is famous for dirty sound output, this is created by interference of the RF modulator component in the board as well as a wide open audio input on the chip. So I started looking for options.
One of the great options I found is the SAMMICH SID, this little device was designed by Wilba in Autralia, he has many cool designs. The SAMMICH SID is a dual SID chip synthesizer running on a MIDIBox system. But this little box is also a bit dirty. So I had to choice but to start tweaking my beloved C-64. Of course I went to ebay to get me another one I could work with, take it apart and destroy it if necessary. This old machines are not very happy with modifications so I didn’t want to kill my working C-64.
The cool things about these machines is that they are very simple to understand and all information, manuals, compilers and schematics are widely available with a simple search.
So these are my stories about hacking the Commodore 64!
First things first. After playing with the chip programatically, I created a simple program that access all settings of the SID chip and played a simple melody. This was not very useful other than allowing me to explore the different characteristics of the chip. Then I found a great solution for control. The MSSIAH SID MIDI software by 8 bit ventures. This cool little program turns the C-64 in to a full featured analog synthesizer and sequencer with a MIDI input. This is the perfect solution for control. I also noticed that ATARI made a sound cartridge with some of these features but without a MIDI input. Now all I had to do is deal with the audio portion of things.
The MSSIAH also supports the addition of a second SID via chip select for stereo purposes or the use of 6 oscillators, 3 per chip. This is done by piggybacking two chips in the same SID socket of the C-64 using the SID2SID circuit board also manufactured by 8 bit ventures.
— To be continued —