The MOS Technology Paula is a custom chip of the Commodore Amiga 16-bit platform. Like the others (and with Amiga being Spanish for female friend), it is named like a woman and after its function, namely the Ports, Audio and Uart Chip.
Besides audio, Paula handles disks, two mice, serial port, and all interrupts on the Amiga. For audio and disks, Paula must be wired to a DMA controller (on the Amiga, the Agnus or Alice chip).
Paula has four audio channels. On each, you can set a volume from 0 to 64, a period (frequency), and play a signed 8-bit PCM sample.
By default, all channels loop. When you want a sample to play once, you either start that sample and very soon set that channel's area to a mute sample (effective once the original sample ends), or stop the channel upon end (which Paula tells your program through one of aforementioned interrupts). The maximum frequency depends on the aforementioned DMA controller.
Finally, channels 1 and 4 are output analog through Paula's AUDL pin, and channels 2 and 3 through AUDR. This means that 2 sounds are always hard left and 2 always hard right, which is a common complaint with headphones.
The Amiga board may add a low-pass filter, but this is not part of Paula. Paula also supports modulations, direct output, and 14-bit samples. The VGMPF currently does not know whether any games use any of that.
Paula is the only Amiga chip that was never revised.
Paula is used in all Amiga-based models.
Most Amiga games play music and sound effects on Paula.
Some Amiga emulators and MOD players (as MOD originated on the Amiga) allow to reduce the stereo separation and do so by default.
- en.wikipedia.org/wiki/Paula_(computer_chip) - Wikipedia.