* Port usage: Write 8bit unsigned sample data to Port FFxxh. The D/A converter is mono and has only one channel (mixing multiple channels is to be done by software).
* The Amdrum software uses port FFxxh. The playback routine also scans the keyboard. The lower 8-bits of the I/O port come from the last value of the C register used to scan the keyboard.
Partial dissassembly of player:
exx
ld a,(bc)
add a,(hl)
ex de,hl
add a,(hl)
inc hl
ex de,hl
inc bc
add a,80h
inc hl
exx
out (c),a
ld b,0f6h
in a,(c)
ld c,a
xor 05h
out (c),a
ld a,0f4h
in a,(66h)
ld (404eh),a
out (c),c
ld b,0ffh
nop
nop
nop
exx
ld a,(bc)
add a,(hl)
ex de,hl
add a,(hl)
inc hl
ex de,hl
inc bc
add a,80h
inc hl
exx
out (c),a
The five chips on the single-sided PCB are:
* [[Media:ZN428.pdf|ZN428 Datasheet]] - 8bit D/A Converter
* [[Media:TL064.pdf|TL064 Datasheet]] - Quad Amplifier
== Partial dissassembly of player ==
exx
ld a,(bc)
add a,(hl)
ex de,hl
add a,(hl)
inc hl
ex de,hl
inc bc
add a,80h
inc hl
exx
out (c),a
ld b,0f6h
in a,(c)
ld c,a
xor 05h
out (c),a
ld a,0f4h
in a,(66h)
ld (404eh),a
out (c),c
ld b,0ffh
nop
nop
nop
exx
ld a,(bc)
add a,(hl)
ex de,hl
add a,(hl)
inc hl
ex de,hl
inc bc
add a,80h
inc hl
exx
out (c),a
== Kits ==