82 lines
3.5 KiB
Markdown
82 lines
3.5 KiB
Markdown
# General Instrument AY-3-8910
|
|
|
|
this chip was used in many home computers (ZX Spectrum, MSX, Amstrad CPC, Atari ST, etc.), video game consoles (Intellivision and Vectrex), arcade boards and even slot machines!
|
|
|
|
it is a 3-channel square/noise/envelope sound generator. the chip's powerful sound comes from the envelope...
|
|
|
|
the AY-3-8914 variant was used in Intellivision, which is pretty much an AY with 4 level envelope volume per channel and different register format.
|
|
|
|
Furnace is capable of doing software sample playback on AY-3-8910, where all 3 channels can play 4-bit PCM samples (at the cost of a very high CPU usage).
|
|
|
|
## effects
|
|
|
|
- `20xx`: **set channel mode.**
|
|
- `0`: square
|
|
- `1`: noise
|
|
- `2`: square and noise
|
|
- `3`: envelope
|
|
- `4`: envelope and square
|
|
- `5`: envelope and noise
|
|
- `6`: envelope and square and noise
|
|
- `7`: nothing
|
|
- `21xx`: **set noise frequency.** range is `0` to `1F`.
|
|
- `22xy`: **set envelope mode.**
|
|
- `x` sets the envelope shape:
|
|
- `0`: `\___` decay
|
|
- `4`: `/___` attack once
|
|
- `8`: `\\\\` saw
|
|
- `9`: `\___` decay
|
|
- `A`: `\/\/` inverse obelisco
|
|
- `B`: `\¯¯¯` decay once
|
|
- `C`: `////` inverse saw
|
|
- `D`: `/¯¯¯` attack
|
|
- `E`: `/\/\` obelisco
|
|
- `F`: `/___` attack once
|
|
- if `y` is 1 then the envelope will affect this channel.
|
|
- `23xx`: **set envelope period low byte.**
|
|
- `24xx`: **set envelope period high byte.**
|
|
- `25xx`: **slide envelope period up.**
|
|
- `26xx`: **slide envelope period down.**
|
|
- `29xy`: **enable auto-envelope mode.**
|
|
- in this mode the envelope period is set to the channel's notes, multiplied by a fraction.
|
|
- `x` is the numerator.
|
|
- `y` is the denominator.
|
|
- if `x` or `y` are 0 this will disable auto-envelope mode.
|
|
- `2Exx`: **write to I/O port A.**
|
|
- this changes the port's mode to "write". make sure you have connected something to it.
|
|
- `2Fxx`: **write to I/O port B.**
|
|
- this changes the port's mode to "write". make sure you have connected something to it.
|
|
|
|
## what is obelisco
|
|
|
|
it's a name I use for a spiky waveform that starts low.
|
|
|
|
its origin is a wavetable that comes in DefleMask that happens to be called Obelisco.
|
|
|
|
## AY derivative modes
|
|
|
|
AY-3-810 was an absurdly popular chip that was blessed with many third-party clones, licensed or not.
|
|
|
|
- the AY-3-8914 variant was used in Intellivision, which is pretty much an 8910 with 4 level envelope volume per channel and different register format.
|
|
- Yamaha YM2149 was an AY-3-8910 clone released in 1983. it's almost identical to AY with minor differences being: higher hardware envelope step resolution (16 vs 32), half-clock mode when voltage level is low, much stronger DC offset and cleaner, but softer output.
|
|
- Sunsoft 5B is YM2149 clone with half-clock mode forced on.
|
|
|
|
## info
|
|
|
|
this chip uses the [AY-3-8910](../4-instrument/ay8910.md) instrument editor.
|
|
|
|
## chip config
|
|
|
|
the following options are available in the Chip Manager window:
|
|
|
|
- **Clock rate**: sets the rate at which the chip will run.
|
|
- **Chip type**: changes the chip model.
|
|
- AY-3-8910: the original model.
|
|
- YM2149(F): Yamaha clone with higher envelope resolution and a different volume curve.
|
|
- Sunsoft 5B: a special model found in one of Sunsoft's Famicom cartridges.
|
|
- AY-3-8914: scrambled registers. has envelope volume control.
|
|
- **Stereo**: enable stereo output. channel 1 is output left, channel 2 is output center and channel 3 is output right.
|
|
- **Separation**: allows you to set left/right separation.
|
|
- **Half Clock divider**: pulls the half clock pin, running the chip at half the speed.
|
|
- only available in YM2149.
|