Identifying an 1802 system
John Ball
ball.of.john at gmail.com
Sun May 15 23:02:52 CDT 2022
I just received a machine that someone found at a Vancouver second hand
store that I basically told them to buy on the single fact I don't own any
COSMAC machines and I've now had a chance to take it apart and photograph
the boards. It seems to be some sort of a kit system that the previous owner
put into a custom enclosure along with a power supply, a cassette interface
and the keyboard off of some other machine or terminal I can't identify but
the interfacing absolutely screams it was something they had available from
scrap.
It's 1802 based, has a single 2716 EPROM and a pair of Intersil D2114 1024 x
4 SRAM chips. The keyboard interfaces through a CDP1851 PIO. The other
board on the almost empty backplane was a video board and this is what made
me think it's not just a fancy ELF clone. You have six more 2114's and an
MC6847 video display generator. The output of that seems to go to an RF
modulator-on-a-chip and then out to an F-type coax. The cassette interface
is soldered directly to the backplane but its edge connector pinout is
awfully similar to the Commodre C2N interface. The boards are all nicely
made photo etch with drilled and plated vias which leads me to believe this
was a purchased kit system and the chips all date to between 1979 and 1982
but the one thing I am missing is a brand or trademark so I don't even know
what I'm looking at. The only thing I got to go on is the name "Color
Machine" which I have not yet found anything about. I have not yet had a
chance to dump the EPROM and I'm still testing to make sure nothing will
blow up in a smoke test, plus I need to dig out a monitor with RF. I have
posted board photos over in
https://forum.vcfed.org/index.php?threads/unknown-1802-based-system.1237931/
post-1256906 in the hopes someone recognizes it but does this look familiar
to anyone here?
-John
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