A3630 (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.)


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.