Fist II: The Legend Continues

Music

Three tunes, one for each part of the world

The game plays one tune at a time, chosen by where the hero stands ($1247), and loops it for as long as he stays. Press a tune to hear it.

The game's music driver ($F400) ported to JavaScript and played through the site's model of the SID chip. The port was checked against the driver itself, run in a 6502 simulator on the game's bytes: all 25 sound registers after each of 30,000 frames, ten minutes of each tune, match. Tune 1 sweeps the filter, so the player starts with the filter of a 6581, the C64's first sound chip; its cutoff is one chip's, and real 6581s differ widely. The filter sweep follows voice 3's envelope, which the model reads once a frame where the chip would be read part-way through it.

Tune	Where it plays	Speed	Instruments
1	areas 0-7 (scenery set 0, the caves), except the temples (`$11FC`)	a tick every 2 frames	8 (0-7)
2	areas 30-47 (scenery set 2), and the temples (`$11FC`)	a tick every 2 frames	3 (9-11)
3	areas 8-29 (scenery set 1), where the game starts (`$1247`)	a tick every 5 frames	5 (12-16)

Each zone's tune ($1247) comes from a three-byte table, and the temples, area 6, are given tune 2 ($11FC) on their own. The speeds are the tempo table ($F42F).

Brennan has described how he worked at Beam: Fred Milgrom, one of the studio's two founders,⁶ talked him through a game's characters and artwork and "the kind of musical 'feel' that he was after", and Brennan would "head off to my little 4-track to put down as many themes as I could muster". Milgrom's "view of games was very cinematic", he says: "He would make me watch Fellini films, or study Chinese music".¹⁴

The driver

Sequences, patterns and 21-byte instruments

The driver ($F400) runs once a frame from the status-band interrupt. Each voice reads a sequence ($F5BD): play pattern n, repeat a block, or jump back to loop. A pattern is a list of notes, each a note byte ($F68E) (the note in the low four bits, the octave in the next three) and a length byte ($F6C0) that picks one of sixteen lengths ($F4D5). The notes come from a table of one octave ($F4C8), doubled for each octave up. A byte of $80 or more in a pattern changes the instrument ($F683).

There are 17 instruments of 21 bytes ($FE43). An instrument sets the waveform and envelope, and can sweep the pulse width from one of three ramps, glide from note to note, add a vibrato or a trill, and route the voice through the filter with a cutoff that sweeps. Only voice 1 restarts its vibrato with each new note: the instruction that asks for the restart ($F6F0) is not indexed by voice, so voices 2 and 3 keep theirs running.

Sound effects

Samples through the volume register

The sound effects are samples, made by Bruce Bayley, the manual says.¹ A timer interrupt ($3D8B) switches the SID's volume between two levels, and each byte of a sample sets how long until the next switch, through a table of 256 timer periods ($0200). Each switch of the volume makes a click, and the clicks at the right spacing make the sound. The site's model of the SID does not play samples, so they are not heard here.