TylerBarnes
Offline
Dallas, Texas

So I was SIDDUMPing some tunes today and also studying a SID register reference table when I discovered something interesting. The pulse width parameter has a range of 000-FFF with 800 being 50% duty cycle. But why when I look in the sequencers instrument page do I see only 32 values for the duty cycle? What gives? why does MSSIAH's pulse width 28 = hex pulse width 800, and why can't I play with very very thin pulses without resorting to modulation?  I don't want a modulated sound, but I DO want a very thin pulse to emulate a highpass filter sound. I don't see any reason on the face of things that explain such a restriction.

jefftheworld
Offline
Toronto, Ontario, Canada

MSSIAH was designed to be easy and 'musical'. Some of the design choices of the software aren't based on fully harnessing the SID but instead making it hard to fuck stuff up. Unless you know what you're doing a very thin pulse width will sound bad, even then it'll be less commonly used than a pulse width closer to 50/50. My guess is that a range of pulse widths were chosen based on the use-case of a 'traditional' music tool.

Jazzmarazz
Offline
Michigan
jefftheworld wrote:

Some of the design choices of the software aren't based on fully harnessing the SID but instead making it hard to fuck stuff up.

Lol, yeah. Too bad MSSIAH isn't open source, because there would be many mods available. The SID is so much more capable than many other 8-bit parallel-controlled synth chips. One such device comes to mind; the Gameboy CPU. It has nearly the same amount of control registers as the SID, but not as much control. Take for example the Pulse width register as mentioned above:

FF11
   Name     - NR 11 --- AUD1LEN
   Contents - Sound Mode 1 register, Sound length/Wave pattern duty (R/W)

              Only Bits 7-6 can be read.

              Bit 7-6 - Wave Pattern Duty
              Bit 5-0 - Sound length data (t1: 0-63)

              Wave Duty: 00: 12.5% ( _--------_--------_-------- )
                                  01: 25%   ( __-------__-------__------- )
                                  10: 50%   ( ____-----____-----____----- ) (default)
                                  11: 75%   ( ______---______---______--- )

Four configurations. FOUR! Thats just sad...