AGNUS(1)                         DICTIONARY                         AGNUS(1)

CUSTOM_CHIPS : AGNUS, DENISE, PAULA.

            The Amiga has 3 special chips each dedicated to a very specific
      class of tasks. The quality and speed of graphics on the Amiga is
      mainly due to these 3 custom CHIPS.

      AGNUS (Address GeNerator Unit): Agnus is the circuit that deals with
            the memory access for the custom chips. It contains the Direct
            Memory Access (DMA) channel that lets the special chips access
            the memory directly. AGNUS contains also the COPPER and the
            BLITTER. The COPPER is a very simple processor that has only 3
            instructions: MOVE, WAIT, SKIP. MOVE is used to access the
            special registers of the custom CHIPS, and WAIT is used to
            synchronize the MOVE operation with the screen refreshing.
            The BLITTER is a circuit used to move and modify blocks of
            memory. It is used for example to draw line, fill boxes and so
            on.

      DENISE (Display Encoder chip): DENISE is responsible for producing the
            screen display from the screen(s) bitmap, sprite register ...
            If DENISE wasn't there, the 680XX processor would have to spend
            most of its time producing the screen display in Video RAM.

      PAULA (Ports, Audio, Uart and Logic): Paula controls the different
            devices and ports. This includes the serial and parallel ports,
            the audio device and the disk devices.
            UART stands for Universal Asynchronous Receiver/Transmitter.