How many transistors in the 6502 processor?

From: Jim Battle <frustum_at_pacbell.net>
Date: Tue May 8 01:54:12 2001

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_at_pacbell.net
Received on Tue May 08 2001 - 01:54:12 BST