Lode Runner

01 · Music

Music: the gold motifs

Collecting the last gold queues one of ten short motifs. A countdown chooses the motif. $6410, $641D, $643A.

A separate pitch offset changes after ten completed rooms. The offset cycles through 2–11, then returns to 2. The motif buttons use offset 2; “High transpose” plays motif 2 at offset 11.

02 · Notes and voices

Two SID voices

The queued music uses SID voices two and three with the original frequency tables. A negative harmony byte detunes the third voice by subtracting 128 from the second voice’s frequency word. $9521, $9546.

The stored envelope bytes do not change the queue’s sustain/release setting. The player reads each event’s fourth byte and then replaces that byte with a fixed value. $6319.

High pitch offsets can reach beyond the 37 stored frequency words. The “High transpose” button plays the adjacent bytes that the driver then reads. Some produce very low frequencies that laptop and phone speakers barely reproduce.

Playback uses the site’s PAL SID model. The game’s roughly 60 Hz CIA queue updates are grouped into video frames. Gameplay effects on voice one and timing within a video frame are omitted.

03 · Editions

Disk and cartridge motifs

The player above uses the disk’s ten motifs. The cartridge has its own sound directory and advances the pitch after seven room completions. Its selection cycle was checked across 70 completions. The Editions tab compares the engines and links their evidence.