Here we are again with another Code Notes entry dear reader, and time to look at another example of regular users programming the C64 despite the author’s claims that it wasn’t possible. Music is an important element of demos and we’ve previously looked at demos with both ripped and original music in the past but not sampled sound. So let’s look at and, just as importantly in this case, listen to something from a couple of bedroom developers who went on to full time jobs in the games industry based on what they learnt with the C64.
A Commodore 64 demo released in 1988
Programming, graphics and sampling by Ash & Dave
Original music by Kraftwork
The title Electric Cafe is taken from the Kraftwerk album of the same name where the short musical loop being played was taken. It’s sampled from Musique Non Stop specifically, a track which has been sampled several times over the years; Sodan and Magician 42’s early Amiga demo Tech Tech was one of the first as far as your correspondent is aware but it still reappears from time to time with the most recent being in 2015 as part of Mahoney’s Musik Run/Stop on the C64, possibly revisiting it after his involvement with the North Star And Fairlight Megademo 3. The two rotating heads that bounce around the screen were taken from the same source, being based on the computer generated ones which were rendered for the track’s video.
The scrolling message mentions that developers Ash & Dave had written their own sampling software (The Flipping Fast Super Turbo Sampler, released the same year) and the borrowed hardware they were using was an off-the-shelf product from Commodore, the SFX Sound Sampler, but the data in this demo has been converted to 4-bit samples since those didn’t require external hardware to play back. The technique is simple enough too; when earlier C64s change volume there’s a “pop” (this isn’t a documented feature and was actually fixed on later models, but it can be reinstated in hardware or worked around in software on those machines) so a routine using the NMI interrupt is basically reading data from memory and shovelling it through the volume register very quickly! Since it only needs four bits at a time, the sample data is compacted so there are two values in each byte using the upper and lower nybble.
From C64CD’s point of view, this isn’t a major landmark in C64 demo coding history because the C64 had been playing samples for a few years by the time Electric Cafe was released, with examples ranging from simple routines such as the one used in Holiday Rap by Dzeppa and more complex efforts from SID maestros Rob Hubbard or Chris Huelsbeck where the samples were played alongside the SID chip’s three regular voices to beef up the sound. But this demo is still one of the more memorable efforts from that era as much for the graphics as it is the cleanly looped sample.
 We’ve mentioned Rob Hubbard’s history as an average user who learnt to program with the C64 and went on to be a commercial musician, and Chris Huelsbeck is another example of that happening; his big break was a 1986 release called Shades which won the a competition in German C64-specific magazine 64’er. We will doubtless return to his work in more detail at some point in the future, dear reader.