> From: Al Kossow
> we have one
> ...
> i'll request access to it to shoot the panel
Excellent! That's currently the worst image of all of the ones on the page,
so a good one will really count. Thanks!
(Although I am a bit curious at to why the Museum's Web site doesn't offer
the option of larger images? If so, that would have been all I needed - the
existing image is square on from the front, so if larger, that would have
been perfect.)
I anyone has a TC15, the existing picture of that one is also pretty bad,
(hint, hint :-).
> there's a cool picture of a PDP-15 here:
> http://www.chilton-computing.org.uk/gallery/ral/orig/r12588.jpg
Yeah, I think that image (definitely that machine) was discussed in a prior
message in this thread. That image shows the RF15 on the left, the VT15 on
the right, and that one in the middle is the unidentified mystery one we have
a bunch of images of.
Noel
Hi Guys
I'd like to catalog my growing list of panels etc. and
the data I have on them.
Some of course I may never make and others I will.
A number of you are connected to museums and would have come
across this issue.
Perhaps you could advise.
Rod (Panelman) Smallwood
Just posting this here in case it reaches different eyes than the forums. ?I had an epiphany yesterday and realized someone on ebay had a GT-6144 as part of an overpriced auction for a Digital Group system. ?They actually agreed to separate it and I will have it in my hands within a couple of weeks. ?I was wondering how rare these are? ?SWTPC stuff seems to be pretty scarce on ebay generally.
I'm wondering if any of you have ever used one of these, esp. in conjunction with a SWTPC system? ?Wondering how much grief I have to get into to hook one up and get it working. ?I know they require their own power supply.. I'm thinking I can use the spare P-97 I have or a spare 6800 PS. ?But I'm leery of modding my original CT1024 heavily. ?Might be time to build up my third one.
Getting pretty close to having this 6800 all kitted out.. just need the PR40 and AC30 and we are there I think. :)
Sent from my Samsung device
I've a question. ?I've now got my CT1024 working properly with my 6800.. is there an easy way to load txt loader files into it while it is still connected to the CT? ?Or do I have to load something in via PC first and then swap cables?
Sent from my Samsung device
-------- Original message --------
From: Pontus Pihlgren <pontus at Update.UU.SE>
Date: 2016-08-11 11:27 PM (GMT-08:00)
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
Subject: Re: SWTPC 6800
Very interresting read, thank you Ethan.
/P
On Tue, Aug 09, 2016 at 10:55:54AM -0400, Ethan Dicks wrote:
> On Fri, Aug 5, 2016 at 2:58 PM, Chris Elmquist <chrise at pobox.com> wrote:
> > On Friday (08/05/2016 at 06:50PM +0000), tony duell wrote:
> >>
> >> Am I the only person who rarely, if ever, has RS232 problems?
> >
> > No.? ;-)
>
> No, but I used to manufacture sync serial hardware and have deep
> knowledge of how async serial in general, and RS-232/EIA works in
> particular, and still have all the test gear from 30 years ago.? I get
> why people find serial comms frustrating and do not take my
> experiences as "typical".
>
> I pretty much don't hook up anything new that isn't on a "traffic
> light".? I have several - DE9-DE9 for modern stuff, and multiple
> DB25-DB25 for old and new stuff.? *Mostly*, if you plug everything in
> and you get at least TxD and RxD to light up, you at least have
> figured out where the primary gozintas and gozoutas go and can stop
> adding null-modem adapters.? Past that, you have to know if either end
> requires hardware handshaking and either plumb the right signals
> (vintage setup documentation is invaluable for this) or bridge the
> appropriate lines (documentation again) so that one or both sides
> _thinks_ there's hardware handshaking.? If you defeat it, you might
> run into overrun conditions, but at least you should be able to
> establish basic comms and pass a few characters.? To that end, you do
> have to match speeds on both sides, and the usual best place to start
> is 8-N-1 for data bits, parity, and stop bits.? I've run into multiple
> situations where 7-E-1 or 7-N-1 is the right answer.? With enough
> experience, the "baud barf" from mismatched speeds takes on an often
> recognizable pattern that can be used to quickly figure out what the
> speed ought to be, but lacking instrumentation like a serial analyzer
> or an oscilloscope, one can try "all the speeds" until cleartext comes
> through.? I also try the speeds in "most popular order", 9600, 1200,
> 300, 2400, 4800, 19200, 600... in the hopes of saving time.? Every
> once in a while, you run into some oddball stuff, like 9600/150, etc.,
> split speeds from the days of timesharing setups where the CPU wanted
> to get data to the users as fast as possible but wanted to minimize
> input interrupts and more closely match the input flow to (slow) human
> typing speeds.? This wasn't common with microcomputers, but I've seen
> it with PDP-11 and PDP-8 setups and isn't something to look for first,
> but it does exist and highlights how strange things can get if all
> you've ever done is plug a high speed modem into a PC for dial-up
> internet.
>
> One important tip about USB serial dongles (and some laptops DE9
> serial ports) - I've had problems with some of them and 1970s gear
> because the EIA/RS-232C (1969) level specification is +5V to +15V for
> space (0) and -15V to -5V for mark (1) (with +/-3V min sensitivity)
> and a lot of old gear is expecting +/-12V and not happy with
> lower-voltage lines and thin wires that don't help signal losses.? One
> case in particular was a 1977-era Bridgeport Series II CNC mill with a
> LSI-11/03 CPU and a lot of custom Bridgeport boards.? Everyone else
> who tried to talk to the Bridgeport before me had zero success.? I
> checked all the things on the list and finally pulled out the laptop
> and set up a Dell desktop which worked the first time.? When
> connecting to pre-1982 gear, I'd definitely try it from a desktop if a
> laptop is just not working.? Checking the lines with an oscilloscope
> could also help verify this what's giving the grief (I did not have
> one handy when we were trying to get that CNC mill working).
>
> In terms of serial analyzers, there are several types out there, and
> the ones that I've had the most time on are the HP 4951/4952 series.
> There are different models with different features, but if you are
> going to shop for one, ensure it comes with the "keyboard lid" because
> that's where the line drivers and serial connectors are.? The large
> connector on the back goes to a "pod" that happens to snap on the
> front of the unit when the keyboard is flipped up.? It's much easier
> to find the base units than loose pods, IME.? Check which pod.? I've
> seen many with DB25s, which is probably what you want, but I've also
> seen DC-37 connectors, and non-EIA (RS-232) level shifters.? The good
> news is that among these different models, the pods should be
> interchangable, so if you end up picking up 2 units (not unusual) with
> different base capabilities (some have DC-150 cassette tape, some have
> 3.5" floppy, plus some minor differences) and only one has a DB25 EIA
> pod, you can at least migrate it between the units.? I find the serial
> analyzers invaluable for snooping on the details of what's happening
> on the wire, but any analyzers I have seen have a handy "autoconfig"
> button to sniff traffic and configure the line for monitoring, so it's
> often a quick click to get all the parameters if you don't already
> know them.? Where they really shine is looking for troubles at the
> application layer, debugging Kermit or XMODEM traffic that isn't
> working for any obvious reason.? The advanced stuff you can do is to
> write programs for some analyzers to simulate a host or a client for
> software debugging or to reproduce a problem for deeper analysis -
> this is far beyond the usual "why can't I get this terminal working
> with this vintage machine" but when you need it, you need it.
>
> In summary, I start by scoping the line with an LED traffic light
> (swapping lines or making custom cables where necessary), then move on
> the speed and parity settings (and changing the easier-to-change end),
> then look deeper when the easy stuff doesn't work.? Easy problems take
> minutes or less.? Hard problems can take a long time to resolve.
>
> -ethan
Normally I manage to repair the SMPSU that I dive into. But this time I
must admit that I am defeated.
It is a VT100 PSU (H7831). I tested it with dummy loads and it worked fine.
But when used in the terminal with the Basic Video board and monitor board
it gives a jumpy picture. Both horizontally and vertically. First I thought
that it was related to the monitor board but soon recognised that the +12 V
had a most peculiar waveform on it:
http://i.imgur.com/d0z0NQS.jpghttp://i.imgur.com/gQqmSN5.jpghttp://i.imgur.com/P0dt5y1.jpg
This waveform is only present on the +12V, not the +5V, not the -12V or
-23V.
So I connected just the Basic video board and a variable dummy load instead
of the monitor board. I used a Variac on the input. It turned out that
there were no problems now with the +12V. Until I pulled out and reinserted
the keyboard. Then it was there. If I lowered the input voltage it was
impossible to provoke this problem and also if I increased the +12V load.
Further testing also gave that putting a few amps extra load on the +5V
also made it resistant to this type of failure mode.
The amplitude and frequency of this waveform is shifting by +12V loading
and AC input voltage.
The VT100 SMPSU is a primary switcher regulating the +5V. Then the +12V is
handled by a secondary switcher which is synchronised with the primary
switcher. The other voltages have linear regulators.
It looks to me that something in the regulation circuitry is not behaving,
thus oscillating. But what component has failed (or is out of spec)? I
checked transistors. I checked the waveform from the 555 chip and ramp
voltage input to the 555. But I cannot figure out what the problem is.
I checked the 560uF output capacitor but my LCR meter said it was in good
shape. Around 700 uF and very low ESR.
I was thinking of breaking up the feedback loop and see what happens, using
an external +12V as an input to the regulator rather than the generated
+12V. But hasn't got there yet.
Anyone seen this type of behaviour? Tony, do you have some piece of good
advice?
/Mattis
> From: Mattis Lind
>> To start with, there's this image:
>>
>> http://homepages.inf.ed.ac.uk/gdmr/Historical/Photos/1980.08-PDP1540.jpg
>>
>> That's clearly an FP15 on the lower left, and I have identified the
>> center one as a TC15, but what are the other two?
OK, I have identified the one on the far right as a VT15. (Crappy image from
DEC documentation added to the page - can someone provide a better one? I've
looked online but the ones I've found are either at a steep angle, or have
a corner missing, or something.)
(And I'm still hoping for an RK08 or RF11 image! ;-)
The other one seems to be the same as this one:
> http://www.hal1.se/Rolfs_web/Rolfs_images/1975_1/pages/7503%2003.htm
>
> The panel to the left is RF15 and the right is TC15. But what is the
> middle one?
which is in quite a few PDP-15 images, but still un-identified.
It seems to be always near the CPU, so perhaps it's a panel for the memory
management, or something like that? I've looked through some of the manuals
on BitSavers, and I've yet to turn it up, although the block diagram on page
2-3 of the PDP-15 Installation Manual shows an 'indicator [panel]' (no
further info on it, alas) in that location, which is probably it.
There aren't that many devices in that system, so there are only a few
possibilities: BA15 (paper tape controller), DW15A (bus converter), KE15
(extended arithmetic), MM15-A and MK15-A (memory). It might also be a BD15,
whatever that might be (seems to include a D/A, from what little I can find
on it online), since that was listed as having an insert for it.
Noel
$$ if you have an IBM 2501 or similar looking punchcard reader and would
like to rent it from sept 1-9th. I would expect you'd deliver it and set
up so it reads cards, and as a bonus can print cards that "say something on
them", understanding that was not how they were originally used. This is
for a SCI FI channel show.
Contact me vintagecomputer.net/contact.cfm if you can do this. $$ worth
the trouble. If it does not work, that's possibly ok, but they want a
working reader that at least reads in a stack of cards through the
mechanism.
Bill
I am looking for a ITT Cannon SK-19-21C connector to be able to connect a
Calcomp 565 (IBM1627) or a Houston DP-1.
Does anyone know of a cheaper source than PEI Genesis? They want 116
euros + 25 euros shipping + VAT.
/Mattis
Hi,
a new release of PDP11GUI is online, with lots of enhancements:
- new disk driver RK611 for RK06/RK07
- Support for Robotron A6402 PDP-11/23 clone
- Support for PDP-11/44 with console firmware v3.40C
- after loading of new machine description file,
show "Restart?" message. Default is now a PDP-11 with all peripherals
build in,
not the "minimal" machine.
- added 2K chip size and "single word" in memory tester.
- If windows font magification > 100 %, memory table form disturbed.
- Long running console access now with progress bar and "Abort" button
- serial format (8N1, 7E1 etc) selectable.
- Migration to GitHub, sources available.
Download from https://github.com/j-hoppe/PDP11GUI/releases
Enjoy!
Joerg
All --
Might be a long shot, but I'm looking for a Seattle Computer SCP-300 8086 Support Board for a project I'm working on. I have the memory and CPU, and a Cromemco floppy card but I'm looking for this to complete the set.
If anyone has one that works that they're willing to sell, please let me know. Thanks.
Rich
Sent from my iPhone
