furnace/doc/7-systems/msm6295.md

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2022-10-16 05:53:05 +00:00
# OKI MSM6295
an upgrade from 6258 - it provides 4 ADPCM channels, at max 32 KHz (still no variable pitch though). between late '80s and late '90s, it was one of the most common, if not _the_ most common soundchip used in arcade machines (Capcom, Toaplan, Kaneko, Atari, Tecmo, the list can go on and on...)
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# effects
- `20xx`: **set chip output rate.**
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# config flags
## chip clock rates
like msm6258, msm6295 is an extremely basic ADPCM sound codec. it has no variable frequency rate, it depends on clock rate of a chip itself. furnace supports following rates:
- 1 MHz, resulting sample rate is 7576 Hz
- 1.056 MHz, resulting sample rate is 8000 Hz
- 1.02 MHz, resulting sample rate is 7727 Hz
- 1.193 MHz, resulting sample rate is 9038 Hz
- 0.89 MHz, resulting sample rate is 6742 Hz
- 0.875 MHz, resulting sample rate is 6629 Hz
- 0.9375 MHz resulting sample rate is 7102 Hz
- 1.5 MHz, resulting sample rate is 11364 Hz
- 1.79 MHz, resulting sample rate is 13561 Hz
- 2 MHz, resulting sample rate is 15152 Hz
- 2.112 MHz, resulting sample rate is 16000 Hz
- 3 MHz, resulting sample rate is 22728 Hz
- 3.58 MHz, resulting sample rate is 27122 Hz
- 4 MHz, resulting sample rate is 30304 Hz
- 4.224 MHz resulting sample rate is 32000 Hz
## chip clock divisor
MSM6295 clock rate could be divided by 132 (resulting sample rates above), or by 165. To get a clock rte using divisor of 165, formula is clock rate (in Hz) / 165. Example: 1 MHz MSM6295 in 165 divisor mode results in output rate of 6060 Hz.