7 May
2001
7 May
'01
6:54 p.m.
At 10:48 AM 5/6/01 -0600, you wrote:
I doubt it was really 68K transistors. If you multiply
out the number of
transistors needed to implement the registers and counters, then add 50%
for the
ALU and double the whole thing for the control logic, you'll probably have as
good a count.
Don't forget that the 68K was microcoded; lots and lots of transistors were
used just for that. In fact, I recall reading that it was described as
"68000 potential transistors" because otherwise the transistor count would
have been dependent on the number of 1's or 0's in the microcode store.
I found transistor counts for a few other processors from a book I have on
my shelf:
MC6800 -- 6000, 57.5%
MC68000 -- 60000, 69%
IAPX 432 -- 150000, 84% (two chips)
MC68020 -- 192000, 70%
IAPX 386 -- 275000, 70.5%
(% is portion of chip dedicated to control logic [vs datapath])
From "The Architecture of Microprocessors", Fracois Anceau, p. 107
This book is in large part based on reverse engineering microprocessors
using a microphotographs (or is that photomicrographs?)
-----
Jim Battle == frustum(a)pacbell.net