Magic sound short description
A[10 9 8 5 3 2 1 0]
0 X X 0 X X X X The board
selected.
0 0 0 0 r r r r RW DMA 8237
rrrr is reg number
D[7..0] Data
0 0 1 0 1 0 r r -W TIMER 8254 CHANNELS
0,1,2
rr
is reg number
D[7..0] Data
0 0 1 0 0 1 r r -W TIMER 8254
CHANNELS 3, and DAC
nn is reg number
D[7..0] Data
0 1 0 0 X X c c -W VOLUME CONTROL
cc is
channel number
D[5..0] Volume
0 1 1 0 c c m m -W MAPPER
cc is
channel number
mm is mappers page register
D[5..0] inverted page number
After reset timers do not work untill first write to its
regs
After dma end (tc signal) the nmi to z80
generated