Boards

                                 A4000 Boards

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* A3640 Reference                              (See Tips.)

  The A3640 is the stock 68040 processor board that comes with most A4000s.
  It contains a 25 MHz 68040; some boards came with the 68LC040, which is a
  68040 with no built-in math coprocessor functions. The A4000 User's Guide
  has instructions on upgrading from a 68EC040, which has no math coprocessor
  or memory management unit (if any A4000s were ever shipped with 68EC040
  processors, there were very few of them). Some A3640 boards (notably,
  revision 3.1 boards with U209 marked as "-02" or "-03") can be used in
  A3000 or A3000 tower computers.

  Jumpers:

    J100: Enable CDIS* MDIS* (???)
          1-2 Closed and 3-4 Closed: Enable CDIS* MDIS* (default).

    J400: Enable MAPROM: Enable remapping circuit for loading Kickstart
          into Fast RAM with a developer utility program.
          1-2 Closed: MAPROM enabled (default).
          3-4 Closed: MAPROM disabled.

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* 68020/68030 Processor Board Reference        (See Tips.)

  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.

  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.

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* Warp Engine Reference                        (See Tips.)

  The Warp Engine is a popular 68040 processor board that replaces the A3640.
  It includes four 72-pin SIMM sockets and a Fast SCSI-2 host adapter.

  Memory: Any combination of 4M, 8M, 16M, or 32M 72-pin SIMMs, either 32-bit
  or 36-bit wide. Add them starting with SIMM4 and working down to SIMM1. It
  is advised that you put your largest SIMM in the SIMM4 socket.

  SIMM Speed: For a 28 MHz Warp Engine, 80 ns SIMMs are adequate. A 33 MHz
  Warp Engine requires 70 ns SIMMs, while a 40 MHz board needs 60 ns.

  SIMM Types: Single or double-sided SIMMs will work, although the double-
  sided 16M SIMM is not recommended due to high power consumption. (This
  probably also applies to double-sided 32M SIMMs; the Warp Engine manual
  doesn't say so, perhaps because they are very rare at present.)

  Upgrading: All that is required to convert a 28 MHz Warp Engine into a 
  33 MHz or 40 MHz Warp Engine is to replace the oscillator and processor.

  Jumpers:

    JP1: SCSI Termination Power

    JP2:

      A: Mode Select    (Off: 040 enabled, On: 040 disabled)
      B: SIMM Type      (Off: double-sided, On: single-sided)
      C: SIMM Bank Size (Off: 16M, On: 4M)
      D: Wait State     (Off: no wait state, On: 1 wait state)
      E: reserved
      F: MMU Disable    (Off: MMU enabled, On: MMU disabled)
      G: Cache Disable  (Off: caches enabled, On: caches disabled)
      H: SCSI Config (see below)
      J: SCSI Config (see below)
      K: SCSI Config (see below)

    JP3: reserved

    JP4: used for A3000 version *only* (connects to pin 21 of U350)

  SCSI Configuration Jumpers (H, J, K on JP2)

    K  J  H    (0=Open, 1=Closed)
    -  -  -

    0  0  0    SCSI autoboot disabled

    0  0  1    10-second delay, LUN scan, not synchronous

    0  1  0    10-second delay, LUN scan, 200 ns synchronous

    0  1  1    10-second delay, LUN scan, 100 ns synchronous

    1  0  0    no delay, LUN scan, 200 ns synchronous

    1  0  1    no delay, LUN scan, 100 ns synchronous

    1  1  0    no delay, no LUN scan, 200 ns synchronous

    1  1  1    (default) no delay, no LUN scan, 100 ns synchronous

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* A2320 "Amber" Reference

  The A2320 is a video deinterlacer board originally built for the A2000. It
  is essentially the motherboard deinterlacer circuitry from the A3000 on a
  board. Based on the Amber chip used in the A3000, the board is often
  referred to as the Amber board. Physically, the board is designed to fit
  into the video slot of an A2000. Electrically, it works fine in an A4000.

  Why would you need a separate deinterlacer board when the A4000 already has
  AGA circuitry that can scan-double? If you have a VGA or multisync monitor,
  there are two main reasons:

  A. Not all programs can be mode-promoted to "double" screens through
     software (games, for instance). The Amber board will scan-double all
     15.75 kHz screens.

  B. The AGA "double" modes are not truly double in frequency. A 640x200
     "doubled" screen syncs at about 27.5 kHz, not the 31.5 kHz that you'd
     expect. Some multisync monitors can't sync this low. With an Amber
     board, the output is 31.5 kHz, the same as "stock" VGA.

  Physical Mounting

  A modified "slot cover" can be attached to the back panel of the Amber board
  to allow it to be attached securely to an A4000 slot. You'll also need to
  trim a bit off the "top" of the Amber's metal panel to allow clearance for
  the A4000 case (a nibbling tool is useful here).

  Don't remove the enable/disable switch! The Amber gets confused by some of
  the "doubled" screen modes, and rather than passing them through, tries to
  double them to 55 kHz or above! On these modes, you'll need the disable
  switch to force the board to pass the video through. (Productivity mode is
  passed through correctly, though.)

  Disadvantages

  The Amber board was designed before AGA came out, and doesn't really under-
  stand AGA. As noted above, some modes are not passed through properly unless
  the board is disabled with the switch. Also, I believe that AGA screens with
  more than 32 colors or HAM-6 will have the colors quantized to a certain
  degree, although I haven't really been able to test this (it hasn't been a
  problem so far). Games that use the AGA color abilities but don't allow for
  promoting their screens to doubled modes are the only likely sources for
  this trouble.

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