furnace/papers/doc/7-systems/saa1099.md

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2022-01-16 06:10:43 +00:00
# Philips SAA1099
this was used by the Game Blaster and SAM Coupé. it's pretty similar to the AY-3-8910, but has stereo sound, twice the channels and two envelopes, both of which are highly flexible.
# effects
- `10xy`: set channel mode.
- `x` toggles noise.
- `y` toggles square.
- this effect affects either the first 3 or last 3 channels, depending on where it is placed.
- `11xx`: set noise frequency.
- this effect affects either the first 3 or last 3 channels, depending on where it is placed.
- `12xx`: setup envelope. this is a bitmask.
- bit 7 toggles the envelope.
- bit 5 toggles whether to use a fixed frequency or lock to the frequency of channel 2 or 5.
- bit 4 sets the envelope resolution.
- bits 1 to 3 set the envelope shape:
- `000`: always off
- `001`: always on
- `010`: down
- `011`: down loop (saw)
- `100`: up down
- `101`: up down loop (triangle)
- `110`: up then off
- `111`: up loop (reverse saw)
- bit 0 sets whether the right output will mirror the left one.
- this effect affects either the first 3 or last 3 channels, depending on where it is placed.