[vcf-midatlantic] Weekend workshop report

Jeffrey Brace ark72axow at gmail.com
Sun Jun 11 23:34:17 EDT 2017


Nice work Mike! It's nice to have working machines for displaying at the
museum! :-D


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On Sun, Jun 11, 2017 at 10:46 PM, Mike Loewen via vcf-midatlantic <
vcf-midatlantic at lists.vintagecomputerfederation.org> wrote:

>
>    I worked on two projects at the museum, this weekend: my recently
> acquired Eagle IIE micro and the museum's HP 2117F display system.  The
> Eagle is a 4MHZ Z80 system (CP/M) with 64KB RAM and SS 5-1/4" drives.  The
> display was out of adjustment, with a "doubled" presentation.  A quick
> tweak by Ian on one of the video pots fixed that, and I resoldered the
> leads to the reset switch which had been inexplicably cut by a former
> owner.  Nice bright and clear display (green CRT), passes internal diags.
>
>    The HP 2117F is a circa 1983 mini, with a hardware floating point
> processor module.  I pulled the power supply and checked the inside of the
> top cover for the infamous black form: yep.  It hadn't quite started to
> disintegrate, but it was just a matter of time.  I removed the foam and
> glued a plastic shield in its place.  The power supply voltages were close,
> but I adjusted them to spec.
>
>    The system wasn't completing its self-test, and didn't seem to be
> recognizing its RAM.  It turned out to be a missing ribbon cable which is
> supposed to connect the RAM boards (3 boards of 256KW each) to the
> controller board.  I pulled a donor cable from our ugly 2113E hangar queen
> and the memory tests now pass.  I also replaced 3 broken plastic toggles on
> the front panel with parts from the 2113E.  I showed Evan how to toggle in
> a short program from the front panel to make the lights dance, Cylon
> style.  To paraphrase a line from the movie, "Firefox": you MUST think in
> octal.  :-)
>
>    The 2117F is missing a couple of crucial controller cards to connect to
> the peripherals in the cabinet: the HP-IB interface for the hard disc, the
> 7970B tape drive interface, and the interface for the 13037C disc
> controller.  Fortunately, the 2113E has the requisite HP-IB card (12821A)
> so it may be possible to check out the HP-IB drive in the future.
>
>
> Mike Loewen                             mloewen at cpumagic.scol.pa.us
> Old Technology                          http://q7.neurotica.com/Oldtech/
>



-- 
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Jeff Brace
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