68020/68030 Processor Board Reference

-----------------------------------------------------------------------------

  This processor board is the board supplied with the A4000/030. It may
  contain a 68030, 68EC030 (functionally equivalent to the 68030 but without
  a memory management unit), or even a 68020 processor. The 68020 option was
  apparently for an extremely low-cost version of the A4000; it is unlikely
  that any boards using the 68020 were ever sold.

  A possible cost-reduced variation of this processor board has no jumpers.
  This type of board has a PLCC socket for the math coprocessor, which runs
  at the same speed as the processor.

  (See also Tips/Processor Board Mounting.)

  Jumpers

    J100: FPU Select
          1-2 Closed: Use FPU in the PLCC socket.
          2-3 Closed: Use FPU in the PGA socket.

    J101: FPU Clock
          1-2 Closed: Use optional on-board oscillator at U103 for FPU clock.
          2-3 Closed: Use CPU clock as FPU clock.

    J103: MAPROM Enable
          1-2 Closed: MAPROM disabled.
          2-3 Closed: MAPROM enabled (requires U100).

    J201: 68020 Select
          1-2 Closed: 68020 not selected.
          2-3 Closed: 68020 selected.

    J202: 68030 Select
          1-2 Closed: 68030 selected.
          2-3 Closed: 68030 not selected.

    J203: 68020/68030 Select
          1-2 Closed: 68030 selected.
          2-3 Closed: 68020 selected.