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Amiga Custom Chip Paula 8364.jpg
Developer: MOS Technology
Released: 1985
Type: Chip

1.) PCM
2.) PCM
3.) PCM
4.) PCM

The MOS Technology 8364 also known as Paula is a chip which includes logic for audio playback, floppy disk drive control and serial port input/output. It was used in all models of the Commodore Amiga, the Commodore CDTV, the Amiga CD32, and Arcadia.

A 8364 contains the following elements:

  • Digital to Analog converters: four signed 8-bit DMA-driven audio channels. Each of the channels have independent frequency and a 6-bit volume control. Channels 1 and 4 are hard left, channels 2 and 3 are hard right, which is a common complaint, especially with headphones. All channels loop, and if a sample should play only once, then either a "mute" sample area has to be set during play, or the channel has to be stopped on end (which can be detected through below-mentioned interrupts).
  • Disk control: a disk controller to read/write data from/to a floppy disk.
  • UART control: a serial port controller to read/write data from/to a serial port.
  • Pot control: four general purpose I/O ports with counters for Analog to Digital conversion which can be used for reading out analog joysticks.
  • Interrupt control: handles internal and external interrupts
  • DMA request logic: requests DMA cycles from the system DMA controller for the audio and disk controllers

Paula is clocked at a fraction of the CPU clock, so pitches and speeds arranged for one region (PAL or NTSC) will differ by 0.9% on the other region.

Emulation Status

Some Amiga emulators and MOD players (as MOD originated from the Amiga) allow to reduce the stereo separation and do so by default.