https://sta.c64.org/cbm64krnfunc.html https://www.youtube.com/watch?v=wAo4dePJaCE Maus in Basic

https://www.chibiakumas.com/6502/platform3.php#LessonP30 assembly SID_VOL = $d418 V1_FREQ_LO = $d400 V1_FREQ_HI = $d401 V1_CONTROL = $d404 V1_ADSR1 = $d405 V1_ADSR2 = $d406

* = $c000 ; Start address in memory

start:

  lda #15       ; Set max volume
  sta SID_VOL

  lda #$c5      ; Frequency low byte
  sta V1_FREQ_LO
  lda #$28      ; Frequency high byte
  sta V1_FREQ_HI

  lda #$09      ; Attack/Decay (fast attack)
  sta V1_ADSR1
  lda #$00      ; Sustain/Release
  sta V1_ADSR2

  lda #$21      ; Sawtooth wave + Gate ON (Bit 0 = Gate)
  sta V1_CONTROL

  rts           ; Return to BASIC or monitor