21 Jan
2009
21 Jan
'09
9:45 p.m.
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
22 Jan
22 Jan
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
23 Jan
23 Jan
8:58 a.m.
On Jan 22, 2009, at 11:47 AM, Ethan Dicks wrote:
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?
Mine fits this description exactly.
-Dave
--
Dave McGuire
Port Charlotte, FL
1:36 p.m.
On Thu, Jan 22, 2009 at 12:45 AM, Ethan Dicks wrote:
> 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?
They are not ordinary, at least I haven't been able to find any like
them. They are brass taper pins, about .093" at the tip and about 0.1"
higher up. The brass part is important. I tried using the regular
.093" pins and splaying the backside slightly, but it did not work
as well, and the steel or whatever the new pins are made of scratches
up the little brass rings.
> 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?
I looked through the manuals, and there's no information about jumper
lengths or quantities in there, at least beyond what was already reported.
> 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.
According to the student manual, they are DEC #12-5591. According to
the DEC parts list, that's a CM2306. The CM2306 is a 6V 20ma bulb
with a brightness of 0.600mscp. (I'd guess that let them be run off
the same supply as the logic.)
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.
That stuff is also available in the back of the student manual.
Vince
2:14 p.m.
On Fri, Jan 23, 2009 at 4:36 PM, Vincent Slyngstad <vrs at msn.com> wrote:
Ah... important to know! I had thought the eyelets to be steel, but
it sounds like they are plated brass, then.
I had been considering trying molex pins, but apparently that's going
to be a poor choice.
Good to know. Chicago Lamp or someone ought to have something that works.
On Thu, Jan
22, 2009 at 12:45 AM, Ethan Dicks wrote:
>
> 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?
They are not ordinary, at least I haven't been able to find any like them.
They are brass taper pins, about .093" at the tip and about 0.1"
higher up. The brass part is important. I tried using the regular .093"
pins and splaying the backside slightly, but it did not work as well, and
the steel or whatever the new pins are made of scratches up the little brass
rings. I looked through the manuals, and there's no
information about jumper
lengths or quantities in there, at least beyond what was already reported.
OK.
> Oh... one
more thing... does anyone have any idea which bi-pin bulbs
> DEC used on this?
According to the student manual, they are DEC #12-5591. According to the
DEC parts list, that's a CM2306. The CM2306 is a 6V 20ma bulb
with a brightness of 0.600mscp. (I'd guess that let them be run off the same
supply as the logic.)
Probably.
Thanks for the info, Vince,
-ethan
3:17 p.m.
From: "Ethan Dicks"
Sent: Friday, January 23, 2009 2:14 PM
On Fri, Jan 23, 2009 at 4:36 PM, Vincent Slyngstad
<vrs at msn.com> wrote:
>> On Thu, Jan 22, 2009 at 12:45 AM, Ethan Dicks wrote:
>>>
>>> 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?
>
> They are not ordinary, at least I haven't been able to find any like
> them.
> They are brass taper pins, about .093" at the tip and about 0.1"
> higher up. The brass part is important. I tried using the regular .093"
> pins and splaying the backside slightly, but it did not work as well, and
> the steel or whatever the new pins are made of scratches up the little
> brass rings.
BTW, I checked, and the molex pins I tried aren't steel or anything
magnetic. They do have sharp edges, so maybe that's why they appear
to be marring the eyelets.
Ah... important to know! I had thought the eyelets to
be steel, but
it sounds like they are plated brass, then.
I had been considering trying molex pins, but apparently that's going
to be a poor choice.
For what it's worth, mini-banana plugs *do* fit nicely. They have two
or three problems, though. First, the housings are fatter than the
simple pins, so you can't use both of the side-by-side eyelets. That
means you'll end up needing the stackable ones. Second, they are
horribly expensive. Third, they aren't very authentic.
Well, sorta. The 911 patchcord kits sold with for the H9xx and K9xx
mounting panels (logic lab gear) consisted of various color coded
lengths of wire with stackable mini-banana jacks on the ends. So
DEC at least used mini-banana patch-cords at one point, on their
higher end stuff.
Thanks for the info, Vince,
You're welcome!
Vince
22 Feb
22 Feb
11:19 a.m.
From: "Ethan Dicks"
Sent: Friday, January 23, 2009 2:14 PM
On Fri, Jan 23, 2009 at 4:36 PM, Vincent Slyngstad
<vrs at msn.com> wrote:
I gave up looking around for appropriate taper pins, and finally today
I took the time to follow up on another idea that I had. Basically, I
made a plaster molding of a pair of the taper pins, and then I took
some stripped, stranded wire, tinned it, and then stuck it in the
plaster mold, and flowed 63/37 solder down the length to fill the mold.
It's not trivial to get the solder to flow the whole length and cleanly
fill the mold (especially as at first the rosin needs to bubble out),
But I was able to do it, and got a "taper pin" on each end of the wire
that has the right shape, is adequately smooth and soft, and seems to
work nicely.
Of course, it is the silvery color of tin-lead solder, rather than the
brass color of the originals, but it is fairly affordable and reasonably
easy to make.
Vince
BTW, you'll wish you'd used some sort of mold-release when making the
plaster mold, even though they are taper pins. I didn't, because I
wasn't sure what could be used that wouldn't leave an insulating film
on the original taper pins when I was done.
They are not ordinary, at least I haven't
been able to find any like
them.
They are brass taper pins, about .093" at the tip and about 0.1"
higher up. The brass part is important. I tried using the regular .093"
pins and splaying the backside slightly, but it did not work as well, and
the steel or whatever the new pins are made of scratches up the little
brass
rings.
Ah... important to know! I had thought the eyelets to be steel, but
it sounds like they are plated brass, then.
I had been considering trying molex pins, but apparently that's going
to be a poor choice. 
12:15 p.m.
On 22 Feb 2009 at 11:19, Vincent Slyngstad wrote:
Of course, it is the silvery color of tin-lead solder,
rather than the
brass color of the originals, but it is fairly affordable and reasonably
easy to make.
This is one application for which I'd recommend lead-free silver-
bearing solder over leaded solder. Stays shiny longer and is a bit
harder.
--Chuck
2:47 p.m.
From: "Chuck Guzis"
Sent: Sunday, February 22, 2009 12:15 PM
On 22 Feb 2009 at 11:19, Vincent Slyngstad wrote:
Your soldering skills likely exceed mine. All I've ever gotten with
the lead-free solders is grainy balls of yuckiness, so I didn't try
them for this. I'd also expect the higher heat to be harder on the
hook-up wire insulation.
Vince
Of course, it is the silvery color of tin-lead
solder, rather than the
brass color of the originals, but it is fairly affordable and reasonably
easy to make.
This is one application for which I'd recommend lead-free silver-
bearing solder over leaded solder. Stays shiny longer and is a bit
harder. 
3:03 p.m.
I'd also expect the higher heat to be harder on
the hook-up wire insulation.
Wiring insulation that can't withstand soldering temperatures is a real
irritation at times.
Teflon-insulated wire might prove useful in that context, for you.
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
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