Commodore Amiga A2000 - Table 5-4 Data Interpretation in Attach Mode

To modulate only the amplitude of the audio output, you must attach a channel as a
volume modulator. Define the modulator channel's data set as a series of words, each
containing volume information in the following format:
BITS FUNCTION
15 - 7 Not used
6 - 0 Volume information, V6-V0
To modulate only the frequency, you must attach a channel as a period modulator. Define
the modulator channel's data set as a series of words, each containing period information
in the following format:
BITS FUNCTION
15 - 0 Period information, P15-P0
If you want to modulate both period and volume on the same channel, you need to attach
the channel as both a period and volume modulator. For instance, if channel 0 is used to
modulate both the period and frequency of channel 1, you set two attach bits - bit 0 to
modulate the volume and bit 4 to modulate the period. When period and volume are both
modulated, words in the modulator channel's data set are defined alternately as volume
and period information.
The sample set of data in Table 5-4 shows the differences in interpretation of data when a
channel is used directly for audio, when it is attached as volume modulator, when it is
attached as a period modulator, and when it is attached as a modulator of both volume
and period.
Table 5-4: Data Interpretation in Attach Mode
INDEPENDENT MODULATING
DATA (NOT BOTH MODULATING MODULATING
WORDS MODULATING) PERIOD AND VOLUME PERIOD ONLY VOL ONLY
Word 1 |data|data| |vol for other channel| |period| |volume|
Word 2 |data|data| |period for other channel| |period| |volume|
Word 3 |data|data| |volume for other channel| |period| |volume|
Word 4 |data|data| |period for other channel| |period| |volume|
- 146 Audio Hardware -