Pretend
you're Intel. (Only smarter.) How would YOU make a low cost
version of the 8086, in a non-bone-headed way?
Lower clock speeds... kind of a
all-solving solution.
Having a pin compatible processor with lower speed and lower cost is an
invitation to one of the worst kinds of disaster. People will buy the
cheap one, and put it into a machine at the higher speed, claiming "it
works just fine". Then later, when it DOES start acting up, the same
people will talk about how crummy the processors are! YES, that DOES
happen. Somebody recently gave me a "lousy" 32MHz 386 motherboard
because it was "unreliable". Under the glued on heat sink was a 20 MHz
chip. That appears to have been the sole problem.
For my own round as "devil's advocate": On the first motherboard of the
AT, people found that they could speed it up by changing the crystal. On
the next revision, IBM purportedly added code to the ROM that would cause
the machine to refuse to run if the clock speed had changed. Everyone put
down IBM for that. I think that what they did was NECESSARY. Without
doing that, the very same people who would up the clock speed would also
bad-mouth IBM for making unreliable computers when it wouldn't work
reliably, FORGETTING or IGNORING the fact that THEY were responsible for
running the board at a speed higher than it was designed or spec'ed for.
OTOH, I would have loved to see a version of the 386SX that would have
been drop in compatible with a 286. Kensington made some (tiny board
with SX and some minor circuitry), but they were rather expensive at the
time.
--
Fred Cisin cisin(a)xenosoft.com
XenoSoft
http://www.xenosoft.com
2210 Sixth St. (510) 644-9366
Berkeley, CA 94710-2219