22 Jan
2009
22 Jan
'09
8:47 a.m.
On Thu, Jan 22, 2009 at 12:45 AM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
Hi, All,
I was one of the ones lucky enough to get one of the DEC Computer Labs
on ePay last month. Mine finally showed up, and after a quick
inspection, I'm ready to make some cables and hook up some circuits.
Somewhere, I do have the teacher's manual. It was given to me nearly
30 years ago, a thoughtful gift from my step-dad's mother who was the
local high school chem teacher. I haven't seen my copy in years, and
I'm worried it was one of the things I lost in a basement flood in the
1980s. I did a google search and a look through bitsavers and didn't
see anything to download, but I did see that this topic has come up on
the list before. There was a call for scanning the docs some time
back (6 years ago?) but no posting of where said scans might be.
Also, there are Phillip's pictures of the cables on grid paper, so
they look like pretty ordinary crimp pins, but I'm having to guess at
the nominal diameter... 3mm? From the cover of the student manual, it
looks like there are 25-ish of the shortest (brown) jumpers, and fewer
of each longer length, but if anyone has a documented count of the
number of each length of jumper wire, that'd be really nice to know.
So are there scans of the student and teacher's manuals for the
Computer Lab anywhere, and does anyone have a list (including in one
of the manuals) of the normal inventory of jumper leads?
Oh... one more thing... does anyone have any idea which bi-pin bulbs
DEC used on this? I didn 't tear mine apart far enough tonight to get
bulb details.
Thanks,
-ethan
Thanks to Dan Veenaman for this -
<http://www.decodesystems.com/dec-clw.html>. Now I know that at least
one jumper kit is 107 jumpers of varying length (and may be able to
deduce an approximation of spread from a scan of the manual cover).
Also of interest is the GIF of the plugboard - that looks quite handy
for documenting layouts. One other thing that could be of use with it
is to document what gates go with what chip on the back. I didn't
know this all the years I wanted one, but the components in the white
area (as opposed to the ones behind the black plate with the switches
and lights) are surface-mount. Not SO packages, but DIP TTL with the
lower leads splayed out. I expect it's because they didn't want to
mar the front of the lab with protruding pins. I will probably mount
sockets on the board if my testing turns up any blown chips. Without
completely dismantling the innards, I can't get a complete inventory,
but there's at least a couple 7473s and 7420s, and I think the AND/NOR
gates are in a 7450. It's all late-60s TTL from what I can see -
contemporary with the PDP-8/i, down to the switch handles.
I was thinking of a quick "colored-line overlay" of the blank
plugboard with boxes and TTL numbers for those of us who think of TTL
gates as parts of chip packages and not as individual gates - just as
a roadmap of sorts.
I don't know if it's true of all versions of the Computer Lab, but
mine was made in Canada, and there's an internal board, additional to
the linked ones for the plugboard and the switch board, that is wired
between trace cuts on the switch board and mounted to the inside of
the frame with Richardson-head screws. Without tracing the board, I
can't tell exactly what it does, but it appears to be wedged
in-between the 8 data switches and the 8 light bulbs - perhaps the
original version of the switch board lit the lights when you flipped a
switch and the version I have allows you to light lights regardless of
switch positions?
-ethan