# Ensoniq ES5506 (OTTO)

Sample-based synthesis chip used in a bunch of Taito arcade machines and PC sound cards like Soundscape Elite. A variant of it was the heart of the well-known Gravis Ultrasound.

it supports a whooping 32 channels of 16-bit PCM and:

- Real time digital filters
- Frequency interpolation
- Loop start and stop positions for each voice (bidirectional and reverse looping)
- Internal volume multiplication and stereo panning
- Hardware support for envelopes

# effects

- **`10xx`**: set waveform.
- **`11xx`**: set filter mode (0-3)
- **`120x`**: set pause (bit 0). Pauses the sample until the bit is unset, where it will then resume where it left off.
- **`14xx`**: set filter coefficient K1 low byte.
- **`15xx`**: set filter coefficient K1 high byte.
- **`16xx`**: set filter coefficient K2 low byte.
- **`17xx`**: set filter coefficient K2 high byte.
- **`18xx`**: set filter coefficient K1 slide up.
- **`19xx`**: set filter coefficient K1 slide down.
- **`1Axx`**: set filter coefficient K2 slide up.
- **`1Bxx`**: set filter coefficient K2 slide down.
- **`20xx`**: set envelope count.
- **`22xx`**: set envelope left volume ramp.
- **`23xx`**: set envelope right volume ramp.
- **`24xx`**: set envelope filter coefficient K1 ramp.
- **`25xx`**: set envelope filter coefficient K1 ramp (slower).
- **`26xx`**: set envelope filter coefficient K2 ramp.
- **`27xx`**: set envelope filter coefficient K2 ramp (slower).
- **`3xxx`**: set coarse filter coefficient K1. 
- **`4xxx`**: set coarse filter coefficient K2. 
- **`81xx`**: set panning (left channel).
- **`82xx`**: set panning (right channel).
- **`88xx`**: set panning (rear channels).
- **`89xx`**: set panning (rear left channel).
- **`8Axx`**: set panning (rear right channel).
- **`9xxx`**: set sample offset (x256).
- **`DFxx`**: set sample playback direction.