Thread: 68040 Questions
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Old 02 January 2006, 14:46   #2
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Join Date: Jan 2004
Location: Oxford
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If you can afford one get an 060 board. They run much cooler.

If not try to get a particular version of 040 CHIP, or get an 040 board with no chip and source a better one.

Some 68040 chips run much cooler than others. Let me give you some background:

The history of the 68040:(backed up with Motorola / Freescale data)
  • In 1989 it went into production as the XC68040RCxxyy originally a 0.8um masks (D43B, D50D, D98D, E31F) part. These run exceptionally hot even at 25MHz and need heatsinks all the time.
  • In 1995 the 68040 qualified to mc status. It was shrunk to a 0.65um mask (E42k) these parts run hot at 25MHz but dont need heatsinks, famous in MAC circles for overclocking. There are some XC 0.65um parts from 1992-95 with the mask E26A but I am unsure as to their heat dissapation or overclockability.
  • In 2000 the 68040 was shrunk to a 0.57um mask (K63H) these run a lot cooler that all previous parts and again do not need heatsinks at 25MHz+.
  • Finally in 2002 the last MC68040RCxxA mask was made (L88M) production was moved back to MOS11 FAB, again at 0.57um, with increased reliability (which should favour overclocking even more).

There were probably intermediate mask revisions, but I have no information (yet) about them. Some XC chips have a H in their title, e.g.


Not quite sure what the H is.

The MASK revision is printed in the top right hand corner of the chip, it's part of a bigger code which includes the date it was made, where etc. Always check what this is before buying either a 68040 or 68060 because getting chips made with later masks is VERY important.

If you are doing some research on mask versions you may need to add a "0" before the mask numbers to get good search results.

In anyone is reading this and thinking hey I know something else about this, please post.

Last edited by alexh; 02 January 2006 at 14:56.
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