2022-10-16 03:41:50 +00:00
# TI SN76489 (e.g. Sega Master System)
2022-01-16 06:10:43 +00:00
2022-10-16 03:41:50 +00:00
a relatively simple sound chip made by Texas Instruments. a derivative of it is used in Sega's Master System, the predecessor to Genesis.
2022-01-16 06:10:43 +00:00
2023-05-20 22:21:51 +00:00
the original iteration of the SN76489 used in the TI-99/4A computers was clocked at 447 KHz, being able to play as low as 13.670 Hz (A -1). consequently, pitch accuracy for higher notes is compromised.
2022-06-22 20:16:19 +00:00
2022-10-16 03:41:50 +00:00
on the other hand, the chip was clocked at a much higher speed on Master System and Genesis, which makes it rather poor in the bass range.
2022-06-22 20:16:19 +00:00
2022-01-16 06:10:43 +00:00
# effects
2023-06-24 01:13:37 +00:00
- **`20xy`**: set noise mode.
2022-06-22 20:16:19 +00:00
- `x` controls whether to inherit frequency from channel 3.
2022-01-16 06:10:43 +00:00
- 0: use one of 3 preset frequencies (C: A-2; C#: A-3; D: A-4).
- 1: use frequency of channel 3.
- `y` controls whether to select noise or thin pulse.
- 0: thin pulse.
- 1: noise.
