|First use||1990 ?|
|Used on||All systems|
The YM2610 is a sound synthesis and playback chip made by Yamaha, found in all versions of the NeoGeo hardware. It was later merged with other chips in NEO-YSA and NEO-YSA2, which are used on some versions of the NeoGeo CD, the CDZ, the MV1C and on ROM-Only boards.
The YM2610 requires a YM3016 external DAC (Digital to Analog Converter) chip for the FM and ADPCM sounds. The only direct analog output is for the SSG mono sounds. Both analog signals are then mixed together before amplification.
The original YM2610 chip gets quite warm during normal operation.
Sound comes from 3 different generators, each having their own channels:
- SSG (Software Sound Generator): 3 channels
- FM (Frequency Modulation): 4 channels
- ADPCM (Sample playback): 7 channels
Providing 14 channels in total.
- SDD: Z80 data bus
- RAD: ADPCM-A multiplexed address/data
- RMPX: ADPCM-A address/data select
- ROE: APDCM-A data output enable
- RA: ADPCM-A address
- ANA: SSG analog output
- SH1: YM3016 latch 1
- SH2: YM3016 latch 2
- OP0: YM3016 serial data
- PA: ADPCM-B address
- POE: ADPCM-B data output enable
- PMPX: ADPCM-B address/data select
- PAD: ADPCM-B multiplexed address/data
- IRQ: Interrupt request output
- CS: Chip select
- WR: Write
- RD: Read
- SDA: Z80 address bus
- PHI M: Clock input
- PHI S: YM3016 clock output
Multiplexed ADPCM bus
The SDRMPX and SDPMPX signals are used to control latches or the PCM chip in cartridges to demultiplex address and data. When SDROE or SDPOE goes low, SDRAD* and SDPAD* are tristated so that the V ROMs can output data.
- SDRA* for ADPCM-A
|Low to high||0||1||2||3||4||5||6||7||8||9||?||?||?||?|
|High to low||10||11||12||13||14||15||16||17||18||19||20||21||22||23|
- SDPA* for ADPCM-B
|Low to high||0||1||2||3||4||5||6||7||8||9||10||11|
|High to low||12||13||14||15||16||17||18||19||20||21||22||23|
24 address bits allow for 16MiB max V ROMs (without bankswitching).
- A lot of games have several recordings of the same instrument playing different notes, rather than having only one sample and change the ADPCM-B playback frequency to vary its pitch. (Trumpet in Viewpoint, electric guitar in Super Sidekicks). Why ?
- Nazca's sound drivers are able to use the SSG channels for music playback. (Maybe all can ?)
Japanese datasheet: [ajworld.net]
Incomplete/translated datasheet: [YM2610.pdf]