Anyone ever use a CDP1802? Try as he did, Tom Pittman with his Short
register, interrupts and DMA. Seems so simple now. It didn't help that
to display something on a TV screen, crude though it may be.
kept it. I still have my COSMAC Elf II though, and I believe it still
works.
computers using emulators and CPLDs (FPGAs?).
Post by RussellMc ...
In my meager experience, the 8 bit PIC is by
far the ugliest environment ever conceived, but it has it's place when
ruggedness, power efficiency and cost are the driving factors.
Blessed are they who have never dealt with the Fairchild F8.
Weird and wonderful were its ways and there is, hopefully, a special place
for it in outer darkness where it may weep and wail, if not actually gnash
its teeth.
DATASHEET http://datasheets.chipdb.org/Fairchild/F8/fairchild-3850.pdf
http://www.textfiles.com/bitsavers/pdf/fairchild/f8/
Fairchild_-_F3850_Central_Processing_Unit_datasheet_-_1982.pdf
Peripherals http://seanriddle.com/fairchild%20micromachine.pdf
https://wiki2.org/en/Fairchild_F8
http://www.cpushack.com/2013/06/08/cpu-of-the-day-
fairchild-f8-microprocessor/
_______________________
The 1974 introduced NatSemi Scamp aka SCMP aka SC/MP aka ISP-8A/600 ... is
less weird than the F8 and actually quite nice to use, but still rather
strange.
Not many, but marginally enough registers that one COULD buidl a simple
system with no RAM, and someone here did, and a friend of mine had to pick
up the project after the miscreants moved on and try to support an expand a
RAMless system.
Technical description 67 pages
http://www.dos4ever.com/SCMP/SCMP_Technical_Description_Jan76.pdf
https://archive.org/details/bitsavers_nationalscicalDescriptionJan76
_8300762
20 datasheet pages as gifs http://searle.hostei.com/grant/SCMP/index.html
SCMP + NIBL BASIC http://www.dos4ever.com/SCMP/SCMP.html
*Wikipedia*: https://wiki2.org/en/National_Semiconductor_SC/MP
https://wiki2.org/en/National_Semiconductor_SC/MP
he SC/MP was also used as the basis of a single board microcontroller
produced by Science of Cambridge (later Sinclair Research Ltd
<https://wiki2.org/en/Sinclair_Research_Ltd>) called the MK14
<https://wiki2.org/en/MK14>. Montgomery Elevator
<https://wiki2.org/en/Montgomery_Elevator> Co of Moline IL (later purchased
by KONE, Inc <https://wiki2.org/en/KONE,_Inc>) used the SC/MP as the basis
for its first micro processor based elevator controller released in 1975.
There are still many of these units running in buildings across the U.S.A.
______________________
The PIC grew from an early ?GE? NMOS processor that was slightly more
arcane.
_____________________
The MC14500B "1 bit" processor was "rather arcane".
Here is my description of it in my "moment of glory" Jack Ganssle "Embedded
Muse" newsletter in 2008, pages 5 & 6
MC14500B datasheet <http://www.ganssle.com/misc/mc14500datasheet.pdf>
_____________
From: Embedded muse 157 pages 5-6 <http://bit.ly/mc14500b_p5-6>
Russell McMahon submitted: The all time most terrible and
narrowest bus width
"microprocessor", assuming such an exalted title dare be applied, and
assuming that there
has never been a none-bit processor, although any number of mine have
assumed that
apparent state over the decades, was the dread Motorola 14500 "1 bit"
microprocessor.
A perfunctory web search, employing effort worthy of such a device, turns
up a number
of references but neither data sheet, nor seller willing to admit stocking
them.
From memory they achieved their claim to 1 bit status fame by having an
execution unit
which returned a binary true/false when various (and necessarily limited)
tests and
operations were carried out. Presumably (and memory dimly suggests) the
obvious
AND/OR/XOR and I seem to recall a TAD or ADD. The outcome of a test would
enable
or disable the execution of subsequently fetched instructions and the
device would chug
oh so slowly up its memory until some text condition was met, whereupon the
instruction
decoding was reenabled and execution recommenced. All program locations were
ALWAYS accessed sequentially as an endless loop with program flow including
any
conditional jumps being achieved by turning off execution, meandering
through address
space and then reenabling execution when the relevant test of condition
produced a true
result.
From dim recollection, the title "1-bit" was a misnomer as you effectively
built tests of a
width that suited externally using such hardware as requisite.
I never used the device but spent some hours with friends poring over data
sheets
attempting to identify a way in which it could be sensibly and economically
used. As we
never discovered one we were never among the buyers of the 10 or so devices
that I
imagine they sold in this country.
And, when was this? I'd guesstimate, based on other memory cues, about
1981-1982,
although that seems rather late in considering the general state of the art
by then.
RIP 14500
Copyright 2003 by The Ganssle Group. All Rights Reserved. You may
distribute this for
information.
The Ganssle Group, www.ganssle.com
<https://mail.google.com/mail/u/0/www.ganssle.com>
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