4 Apr
2006
4 Apr
'06
6:46 p.m.
Chuck Guzis wrote:
On 4/4/2006 at 10:07 AM Don Y wrote:
I don't think they are the same beasts. But, I think they (or
something with a P/N similar to that) sticks in my mind as a
viable alternative to Z80's at one time...
I probably have a tube of them somewhere in the
garage. I've
"explored" most of the 8085/Z80 variants over the years in
different designs (I recall a 3870?) -- though I haven't touched
one in probably a decade or more...
Hmmm--I've got a couple of the 3870s and I don't believe they're of the
same 8080/Z80 family. IIRC, the original F8 (the
3850) was not a complete
microprocess and required one of several support chips that provided, among
other things, the program counter and memory control logic. (3851, 3852,
But, that's similar to the 8080, 4004, etc. lineage... I can recall
being excited when the 8085 came out with ONBOARD XTAL DRIVER!
Woo-hoo!! :>
3853?) Fairchild later introduced the 3859, which
combined the two
simplest chips (3850, 3851), but Mostek did them one better and combined
the 3850 and one of the more complex support chips--I forget which one; it
may have been the 3856. Again, IIRC (I had only peripheral experience with
the things), the big advantage of the 3870 wasn't the level of integration,
but the steeply lower ROM mask charge over the Fairchild parts. I believe
that Fairchild, knowing a good thing when they saw it, licensed the 3870
from Mostek.
I've got a bunch of the 2.5 MHz NSC800's--I'd love to get my hands on a 4
MHz part. NSC's part suffix numbering system is a bit bizarre and probably
points to a story of a missed objective. The -1 is a 1 MHz part, but the
-3 is 2.5 MHz; the -35 is 3.5 MHz and the -4 is 4 MHz.