I've been trying for the past week to verify that telephony on my teletype
machine (model 33) is functioning properly but the biggest hurdle I am
running into is I have nothing to easily dial into. Everyone I know off hand
either don't have a modem anymore or theirs is a Winmodem which won't work.
There's only one phone line into the residence here and those bluetooth to
cellular POTS bridges are too lossy to make do and connect to a machine
here. There is that youtube video of the model 37 apparently connecting to a
system at the Living Computer Museum in 2013 (MikoF6KZjm0) where they dialed
into a BBS I've never seen listed anywhere but the number listed no longer
seems to work and in the description it states the service is no longer
available. What other public systems are still out there that will work this
speed or possibly better yet, is there anyone out there willing to try a
teletype-to-teletype conversation?
-John
Subject line says it all -- I'm looking for the top/side cover for the
"slim" PDP-11/05. Probably not infeasible to build one, but I figured
I'd ask around first.
Got lucky on a cheap 8KW core plane (H214) on eBay to replace the
damaged one the /05 came with (which we had a discussion about last
year), and everything seems to be working fine other than a completely
dead Boxer fan (a replacement is on the way), I'd like to find the top
cover to help with air flow/cooling. And so I can put things on top of
it :).
Thanks,
Josh
Pictures of the S/130 system I'm building up are at
https://www.flickr.com/photos/131070638 at N02
I think the last I posted here... the cpu was up and running, that was the
first piece I refurbished. I took everything out of the rack and cleaned
that up well, and the cpu has been remounted there.
Yesterday I mounted the 6030 dual 8" floppy drive. It was squeaky clean
inside and at power up everything does what it should. However, I can't
proceed further with it as I have no media. The docs say it uses hard sector
8" floppies, which I believe I can find. However, it specifies 8
sectors/track hard sector floppies - and those I've never heard of. Maybe DG
made them special just for their gear, or, maybe the drive or controller or
software was smart enough to expect the more common 32 hard sector floppies
and knew to only pay attention to every 4th sector hole ;) In any case,
before I spend "real dollar$" on media, if anyone has a single piece of 8
sector hard sectored 8" media I'd love to get one for testing :) Getting the
6030 connected to the cpu took a lot of documentation reading. It would seem
that DG didn't believe in anything plugging in to interface boards. Instead,
interface boards went in the cpu with no external connectors. Then you
wirewrap from the backplane from a given slot to one (of a stack) of paddle
boards bolted to the rear of the cpu chassis. Those paddleboards have edge
connectors, and that's where you connect the device cable. Fun stuff.
I started digging in to refurbishing a 6125 mag tape unit to go with the
above system. It has power supply issues. The schematics I have are similar
but not 100% correct so some guessing was involved. Whenever I turned on the
tape unit, any other things (shop light, oscilloscope, etc.) plugged in to
the same circuit would start randomly turning off and on. That is not a good
sign ;) Earth leakage... Checking the snubber circuit on the mains side of
the transformer led me to suspect a mylar that sat between hot and neutral.
I lifted one leg of it (just for testing) and that problem is definitely
gone. Next problem is the power supply makes a loud ringing noise. I believe
that's usually either ceramic disc capacitors or transformers, but I'm
having a really hard time locating the exact source of the sound. I'm going
to remove the power supply from the metal chassis and hook it up externally
(that's how it goes in the rack anyways) and see if I can tell for sure that
is the issue. Other than that, offline tests all work, so that will be
racked up shortly and cabled to the S/130 cpu.
Next on the list is refurbishing the DG 4084 dual cassette tape unit and
racking that. Something tells me media will be unobtainium for that.
Last step will be to refurbish and install a hard drive, most likely I'll
use a 6050.
So... some progress at least :)
J
> now that I have the better picture, let me see what I can turn up.
Got it! It's the _bottom_ indicator panel from an RP15 disk controller - from
a PDP-15. I think that's the only DEC controller I've ever seen with _two_
indictor panels on it!
And no, the one in the back is not the other RP15 indicator panel; it really
is an RP11.
Noel
> From: Johnny Billquist
> They could be from a PDP-11 or PDP-8 as well.
Not _impossible_ (since the RP11 does have one row of 36 lights - no doubt
because it can be used to read packs written by PDP-10's - it's the shift
register for reading the bit stream off the drive) but I'd say less likely,
given the two rows of 36 bits.
Or maybe not; one is a shift register, the other is a Longitudinal Parity
accumulator, which would also naturally be the same word length.
> The RP11 controller, for example, I seem to remember had panels like
> that.
In fact, I have a picture of an RP11 panel, and... the one in the back _is_
an RP11! Well, knock me over with a feather!
> Can't recall any PDP-8 stuff at the moment, but I'm pretty sure I've
> seen something like that for a PDP-8 as well.
I've seen images of (or worked out the light pattern for) two, the TS08 and
the RK08, and this isn't either one. (Both have only two rows of lights.)
I wonder if there's an RP08? {Checks} Yes, there is. Do we have prints?
{Checks} Yes. Alas, the scans of the connector pages of the prints are
pretty bad, but it doesn't seem to support a display panel.
> From: Vincent Slyngstad
> A higher resolution picture
Oooh, thanks very much, that will be _very_ helpful.
> From: Al Kossow
> They are both disk controller panels.
> The one marked tape controller has "sector word count"
Hmm. Could be; now that I have the better picture, let me see what I can
turn up.
I note the 'sector word count' has 7 bits in it, which kind of implies a
PDP-10 - most PDP-11 disks had 512 bytes / 256 words -> 8 bits. Although
maybe there are a few early ones that had 256 byte sectors, I have this vague
bit set that there were; will have to check that.
I think I'm going to have to create a page for DEC indicator pabels!
Noel
> From: William Degnan
> Of note...
Anyone know what the two indicator panels on top of the large blue box in the
center of this one:
ftp://jhoppe.ddns.net/vcfb2105/content/TB8A3377_large.html
are? They look to be PDP-10 {something}, given what appear to be two rows of
36 lights on the bottom (although they are hard to see clearly), but I
couldn't find a panel like that in my PDP-10 manual.
Noel
> From: Rich Alderson
> You know, the same company that does not have dis[kc]s, but DASD.
Some guy from IBM came to MIT to give a talk about some database system that
they had, and he kept referring to 'DASD'. Puzzled looks. Finally some brave
soul stuck up his hand, and asked was a DASD might be. Quoth the guy, 'round
brown'! :-) He was actually very sharp, and we liked his system, but I don't
recall anything about it, other than that line!
Noel
