Commodore Amiga A1000, Hardware Reference Manual

Page: 156 / 380

The lengths of the data sets of the modulator and the modulated channels are completely
independent.
Channels are attached by the system in a predetermined order, as shown in Table 5-5. To
attach a channel as a modulator, you set its attach bit to 1. If you set either the volume
or period attach bits for a channel, that channel's audio output will be disabled; the
channel will be attached to the next higher channel, as shown in Table 5-5. Because an
attached channel always modulates the next higher numbered channel, you cannot attach
channel 3. Writing a 1 into channel 3's modulate bits only disables its audio output.
Table 5-5: Channel Attachment for Modulation
ADKCON REGISTER
Bit Name Function
7 ATPER3 Use audio channel 3 to modulate nothing
(disables audio output of channel 3)
6 ATPER2 Use audio channel 2 to modulate period
of channel 3
5 ATPER1 Use audio channel 1 to modulate period
of channel 2
4 ATPER0 Use audio channel 0 to modulate period
of channel 1
3 ATVOL3 Use audio channel 3 to modulate nothing
(disables audio output of channel 3)
2 ATVOL2 Use audio channel 2 to modulate volume
of channel 3
1 ATVOL1 Use audio channel 1 to modulate volume
of channel 2
0 ATVOL0 Use audio channel 0 to modulate volume
of channel 1
- Audio Hardware 147 -