On Jun 25, 2012, at 7:04 PM, Andrew Lynch wrote:
Hi Dave
Yes, the conversation on a hobbyist 68040 SBC is continuing on the N8VEM
mailing list. After doing some research on a notional design (MC68040 with
MC68360 in "companion mode") and some bare bones IO (using a Propeller) I
am stunned at how expensive such a design would be. I realize Motorola lost
the hardware price wars in the 1990's and now I know why! This will cost a
fortune to build!
Well, it cuts both ways. The chips were more expensive and are rarer now
because they were produced in lower volume. The causal relationships for
the prices are complex and interdependent at best. They didn't exactly
lose the hardware wars in embedded systems, but that market was so far
dwarfed by the IBM-compatible PC market that it scarcely matters.
The MC68040 is very expensive and the MC68360 is also expensive but at least
there is a "low cost" (<$30) in large SMT-only packages (QFP-240). Ugh.
Even a stripped down SBC is going to be very expensive to build and will
almost certainly require SMT devices. The MC68030 is essentially
unobtainium except for onesie/twosie deals on eBay.
The '040 is expensive new, but I find it to be cheaper and more readily
available on eBay, at least (about $25 each vs $35-$70). I think it's
because no PQFPs of the '040 were (to my knowledge) ever developed, so
while many '030s (especially on Macs) were PQFPs that were never pulled
from dead units. The '040, on the other hand, was
only ever available
in CQFP (which few people like to use) and CPGA, which is a lot
more
recoverable.
My recollection is that the '040 was only available in ceramic because
it ran so damn hot (for the time, anyway). I don't recall the 486
being much better in that respect; every one I saw had at least a
heat sink on it.
I am discovering the fully 32 bit Motorola processors
with MMU are not
"hobbyist friendly" by any stretch. Any help greatly appreciated! Thanks
and have a nice day!
Well, no more so than the equivalent 80x86 CPUs. The 68000 is a little
harder to interface to a bus than an 8086, but people are much more
used to doing the latter. Moving forward, they're all a pain in the
neck.
PS, if you are interested in the 68040 SBC discussion
you are welcome to
join us on the N8VEM mailing list.
I would love to! I never quite figured out how to join, but that's
due to lack of effort on my part. One of these days I'll find some
round tuits and jump aboard.
- Dave