More Soundchip Hacking: Realtime SID delay

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.

11 Responses to “More Soundchip Hacking: Realtime SID delay”

  1. TRUE CHIP TILL DEATH • Chipflip: Realtime SID delay Says:

    […] More Soundchip Hacking: Realtime SID delay « CHIPFLIP. Share […]

  2. peter Says:

    So how long before we have phasing, and chorus type effects? Exciting! Plus its nice to have something the 65 is better at for once!

  3. Neil Says:

    I hate to be anal but it’s “Nijuu” :)

  4. chipflip Says:

    anal made me change it!


  5. yonx Says:

    aah.. i have been waiting for this moment since i first heard the rumors about geirs player some months ago.. it surely lives up to the expectations!!

    baldwins routine is kinda cool as well, but i guess it eat channels and is not as usable in a tune with full instrumentation?

  6. yonxUP Says:

    just read the very nice explanation on baldwin’s http://www.. nice performed trick! can’t really see that it would be CPU-intensive either but what do i know :)
    i hope that we can see this routine reincarnated on the SID in the future with all the dubby features the NES can’t provide..

    • Neil Says:

      Heh, thanks!

      That particular effect isn’t very CPU-intensive. It’s only collecting the register values per-frame and manipulating a point in a circular buffer. It’s probably one of the more efficient bits of my NES driver :)

      I’m currently trying to figure out if it can be done effectively on the C64. Not quite so simple without per-voice volume and hardware ADSR. But I’m determined enough.

  7. From Neil Baldwin to Killer Collectivism: 1980s NES-music « CHIPFLIP Says:

    […] made at his site, work on a new text-based NES music software to make full use of the NES (mentioned before), and he has produced some new music! Don’t miss his last one, Cleptoplank, full-force […]

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