Monday, 17 October 2016

Enhancing & Modernising A4000/040

article from Dave's Amiga Hardware Page

Although the A4000 was the ultimate 'Big Box' Amiga, due to it's age and certain design compromises, there are quite a few performance limitations. These include slow motherboard RAM access (when using the A3640), slow AT-IDE interface and small motherboard RAM capacity. The modifications described here are intended to alleviate these, while also providing a worthwhile performance boost at reasonable cost.

A4000 motherboard and A3640 with all the modifications applied
The Modifications
Below is a list of the modifications. You can do them all together or individually if desired. Most of these link to third party sites or forum discussions.

  1. Remove and replace leaking battery with CR2032 lithium.
  2. Upgrade motherboard RAM to 64MB.
  3. Upgrade Kickstart ROM size to 1MB (machine translated from French).
  4. Upgrade Kickstart to version 3.9, add custom modules.
  5. Upgrade AT-IDE interface from mode 0 to mode 2.
  6. 68030 state machine mod - improve motherboard RAM access speed when using A3640.
  7. Improve ability to overclock the A3640.
  8. Upgrade 68040 to 68060.
  9. Add threaded spacers to support CPU card.Helps ensure the CPU card is firmly attached.
  10. Add headers for cooling fans. A pair of two pin headers can be soldered into existing holes next to power socket, providing 12V.
  11. Add header for reset button. This is soldered to pins 2 & 3 on the battery backed clock chip, and pulls /Fail to ground, resetting the Amiga.
  12. Replace capacitors on A3640. Note I used low profile 'chip' capacitors to allow clearance for 040/060 adaptor. Capacitors on the A4000 motherboard should be checked too.

First Published: April 25th 2015

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