- For the example songs, see PASS (C64).
PASS (Parabola Advanced Synthesis Software, a.k.a. Allegro) was one of the very first Commodore 64 music editors that supported modulations.
Initially, Landwehr spread a demo with 3 classical and 2 own compositions and ordering information; you could order PASS from him for $49.95 by check or money order.
You can arrange 41 sequences (coherent songs) in a script language called Forte, where you enter notes, rests, durations, ties, repetitions, instrument changes, sustain lengths, jumps, and comments and colons for easier reading. You can temporarily or permanently jump to other sequences (like chorus, loop points, or pure instrument changes) and even another voice (as an echo). Cumbersomely, a composition is split over several screen (page) files: every time you want to edit a screen, you have to load the correct one and save it; to hear your composition, you have to compile every screen -- on a slow disk drive.
Instrument-wise, you can set all SID chip registers, detunes, tempo, modulations on pitches, pulse widths and cutoff frequency, and two unique effects called phaser and heavymetal. There are even two ways. There are 3 more editors in the main menu where you can try out settings as the song plays. To change anything inmidst of a composition, you must enter Forte commands.
In phaser and heavymetal, the note frequency is constantly increased by itself and reset after the given duration. They actually sound like arpeggios (if with fixed notes). On each modulation, you select a source and depth. The source may be mouse or paddle movement (unlikely) or the current signal or volume of voice 3. A common trick was to play a melody on voice 3 and copy its current volume to the cutoff frequency. For anything else, you have to sacrifice voice 3 to regularly play extremely low notes with slow envelopes.
In 1984, Landwehr added 4 software vibratos at different speeds as sources, PASS was renamed to Allegro, reduced to $39.95 and licensed to Artworx Software for USA-wide distribution. In 1985, Artworx distributed an Allegro Sampler with over one hour of over 40 user songs for $8.95. Despite rave reviews, PASS became quickly forgotten, possibly in light of Sidplayer. Nevertheless, Landwehr's sound was impressive for 1984 and rediscovered by the European C64 scene in 2008.
The following composers used PASS:
- Bob Landwehr
- Scott Emmons
- Unknown on The Amazing Spider-Man and Captain America in Dr. Doom's Revenge (C64)