The Norwegian composer Geir Tjelta has introduced a new trick for the SID-chip: realtime delay. The output of the third channel of the SID can be recorded, and by delaying the playback of the sample on the “virtual” fourth channel, you get a subtle echo. This routine doesn’t use much CPU-time either. A nice and elegant trick. Get the exe and mp3 here. It needs to run on the old 6581 chip, since this technique for playing samples relies on a bug that was almost fixed with the new 8580 chip.
Another modern way of making automatic echoes is Neil Baldwin‘s routine for his new NES music editor, Nijuu. Instead of sampling sounds, it detects free spaces in the tracks and triggers notes with decreasing volumes. It uses more CPU but sounds more obvious than Tjelta’s echoes. Listen to the MP3.
As a sidenote – Geir and Neil are both chipmusicians from the 1980s having recently returned with a boom. Geir also programs an editor together with GRG, Sid Duzz It, which according to the rumours will include this echo effect along with extensive MIDI support in the next version.
Edit Oct 01: Geir says it will not be included in the new SDI.