I learnerd the following from a very wise brazillian storm-trooper
the (odd) numbers in the motorola chips are small revisions, bug fixes and DIE size changes of previous chips -
68000
Original CPU with 68000 transitors onboard
- 68010
fixed some bugs, thus making some games/software unreliable that used them bugs,
added a couple of fast instruction loops
68020
Whoot 32bit in and out =D
- 68030
added some more cache, revised the die and fixed some bugs, integerated the MMU
68040
Integrated FPU and revised the cach.
- 68050
Designed but never to see silicon
68060
Super Scaler incorperated and Branching instuctions
- 68070
Designed but never to see silicon
between the 040 and 060 releases there was a hugh DIE change, this reduces the power required to push the gates open, but also more cach and other features can be put on the silicon.
the original 040's using the old cach suffer terribly from over-heating failure (especially those old 25mhz units) the latter 40mhz compatible units are made with the same micron size as the 060 and hence run VERY cool, also its wise to not that this particular 040 is 5volts as opposed to the 060's 3.3volts.
however according to the schematic from free scale the 060 can have upto 4.6 volts when clocked to 100mhz
okay... geeking out now.... sorry about that....