> and tried looping back pin 2 to pin 3
>on each serial + modem port and typing some characters, but nothing shows
>up in vterm.
? PDT-11/150 terminal and printer ports ports all require a high on pin
20, DTR, before they can send characters.? I've never used the modem
port on my PDT's but I suspect it requires the typical, pins 6, 8, and
20 wired together. Maybe you need to pull some of these pins high to
loop around?
--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.gleason at comcast.net
Spotted on ebay -
No involvement in the sale - just tagging in case any one on the list has interest.
"Muldivo Digiputer 1968 - Imperial Dialog: IBM Model B"
https://www.ebay.co.uk/itm/203849003806
On Tuesday (03/01/2022 at 04:36PM -0800), Marc Howard via cctech wrote:
> I've got a PDP 11/34 I've never opened up. It's mounted in a H9642
> cabinet. I can't get the bloody thing to extend on the chassis track
> slides.
>
> Is there a catch or lock screw on this unit?
Mine (and we may be learning, is not be a proper configuration) does not
have any release or catch to allow the CPU to slide out. I just grab it
and start pulling and it slides out-- although it does not slide easily.
That could be due to old, stiffened lubricant on the slides.
BUT! make sure you pull out the front foot at the bottom of the rack to keep
the whole rack from tipping forward if you do get the CPU to slide out.
The CPU is a heavy beast and the rack WILL tip forward once the CPU is
out far enough.
Chris
--
Chris Elmquist
If it's mounted in a standard BA11-K, no. You should be able to pull it out partially (sufficient to tip up if you have rotating slides) and then there should be locking-buttons on the slides to prevent further extension accidentally. Depressing those buttons will allow you to completely remove the chassis and its attached inner slides; the outer slides will remain in the rack. Be careful with full extraction -- the power supply is heavy and the chassis is unbalanced. It's really a two-person operation, or one best accomplished with some sort of supporting mechanism (even wooden cribbing if you are so inclined).
If it's anomalously mounted in a BA11-A (like the 11/44) then there is a finger-tab accessible through the front grill on the upper-right that pulls back a spring-loaded side-tab that engages the rack frame to prevent *any* extension whatsoever. Pull that away from the rack-frame and then pull out the chassis.
Of course, it's possible that you simply have rusted slides that are binding, in which case you will simply have to use force. Recommend _pushing_ from the rear if "reasonable yanking" from the front isn't working. Although I've encountered a fair share of rusty slides, all have yielded (slowly) to repeated yanking/pushing, even if only a few centimeters at a time. Penetrating oil applied from the sides will help, but after cleaning and polishing the slides suggest that you use graphite or lithium grease to re-lub when reassembling. Others may have alternative lubrication recommendations.
-----Original Message-----
From: cctech <cctech-bounces at classiccmp.org> On Behalf Of Marc Howard via cctech
Sent: Tuesday, March 1, 2022 7:37 PM
To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: While on the subject of cabinets...
I've got a PDP 11/34 I've never opened up. It's mounted in a H9642 cabinet. I can't get the bloody thing to extend on the chassis track slides.
Is there a catch or lock screw on this unit?
Thanks,
Marc Howard
I am wondering if I have racked my 11/24 correctly.
As you can see here:
https://robs-old-computers.com/2022/02/10/pdp-11-24-progress/ I have put the
CPU at the top and the two RL02 drives underneath.
The problem is that the CPU enclosure catches on the RL02 underneath. There
is a bit of play in the mounting bracket:
https://rjarratt.files.wordpress.com/2022/02/cpu-mounting-bracket.jpg. With
a bit of manipulation I can get the CPU to slide in. However, I am wondering
if I have racked it correctly? I don't think there is room to move the RL02s
down and it would presumably leave a bit of a gap below the CPU. There seems
to be very little clearance between the CPU and the RL02 at the front but
more at the back, but I am sure that the rails are mounted horizontally. Is
it just a matter of tightening the big screws that hold the mounting
brackets to stop the play? If so I am not sure I have a big enough
screwdriver!
Regards
Rob
Hi!
Anyone remember how to use this program that announces itself as "PDT-11
Virtual Terminal Monitor v1.07" ? I found it on a floppy of RT-11 v4.0
with my pile of PDT-11 treasures (which amazingly still seem to read fine
and work wonderfully; disk file timestamps around 1979 - 1982).
I thought maybe it was a term program, since these PDTs were kind of
famous for that sort of deployment, and tried looping back pin 2 to pin 3
on each serial + modem port and typing some characters, but nothing shows
up in vterm. It does come out of some mode into a command mode, I think,
when I send a break to the console. ^C kills it from there and I can get
back to RT.
I found online a DECUS program of the same name (vterm), submitted by DEC
circa 1979, and am wondering if this is the same beastie I've discovered on
my 8" floppy:
https://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/decus/…
; however, when I try to click through that decus website, the actual
packages themselves seem to have been lost! Does anyone know where to
obtain the actual files that came with this 110417 from DECUS? And if I'm
on the right track, here? It would be cool to have this PDT-11 functioning
as God intended if this vterm is actually a terminal emulator type of
thing...
thx
jake
Does anyone have anything on the jumper settings for this drive?
I would like to jumper it so it can read DEC RX01/RX02 floppies.
I am looking at being able to read disks on a non-DEC systems
but I would also like to be able to use it on my Andromeda card
in a real PDP-11.
bill
Hi
????? Is the correct setting:
?????? 1. DS1 on the RD31 and the RX50's move up to DU1 and DU2.
?????? 2. DS3 on the RD31 and the RX50's are DU0 and DU1
I've tried both and it still? tries to access the RD31 and the RX50 at
the same time.
Its on a standrd BA23
R
>> (I have yet to check and see if the KY11-LB asserts SACK if the CPU
>> halts on its own accord - probably 'yes', but that's a project for tomorrow.)
Yes, it does. I toggled in the following program:
5000
5200
776
0
(what, you all can't program a PDP-11 in octal? :-) and hit 'start' and the
SACK light on the UA11 flashed out and came back on when the machine finally
halted.
So then I looked at CPU tech manual for the KD11-E, and the HALT instruction
seems to act exactly like the console has requested a processor halt; it just
sets the HLT RQST signal (see Section 4.5.5 "Operate Instructions").
So, either (console halt, or a HALT instruction) will cause the identical
response in the processor; see Section 4.10.3 "Halt Grant Requests": the CPU
sends HLT GRANT to the console, which returns SACK. As long as SACK is
asserted, the processor waits with its clock inhibited:
"The user can maintain the processor in this inactive state (Halted)
indefinitely. When the HALT switch is released, the user's console releases
BUS SACK L, and the processor continues operation"
This text is obviously for the KY11-LA; the KY11-LB will operate identically:
when the console releases SACK, the processor resumes operation.
> From: Fritz Mueller
>> when I powered the machine on, it turned out that something was
>> asserting SACK when the machine was halted
> That is quite interesting, and not what I would have expected!
Yes, I was quite surprised; I didn't expect that either. Now that I know that
the KY11-LB uses it to talk to the KD11, I can work around it, though.
I'll have to write all this up to warn others about it.
>> The thing that's puzzling me is that the M8264 seems to exactly
>> replicate the functionality of the M9302, with an 'unused' bus grant
>> being turned into a SACK. So I don't understand the point of the M8264.
> I think the only difference would be that since the M8264 is timer
> based, it doesn't need the intact end-to-end path required for
> turnaround. So your bus won't lock even if you have a broken grant
> chain or a poorly behaved or hung device eating grants.
You are right about it being timer-based, but I'm not sure the conclusion
follows, at least exactly as stated.
If there's a broken grant chain, then as you originally pointed out, the M9302
will jam SACK on. The M8264 could not even be there, and nothing would be any
different. Same thing if the CPU asserts a grant in response to a now-removed
interrupt request: the M9302 will jam SACK on, etc, etc.
I'm racking my brain to think up _any_ circumstance in which the M8264 will
assert SACK. in which the M9302 wouldn't. Thinking it through, there has to
be a grant, but it can't get to the M9302 (because otherwise it would do its
thing), but that failure to get there can't be simply a broken grant chain
(ditto). So some device has to be malfunctioning: not passing a grant along,
but eating it. So either a hard-failed component in the grant-passing
circuit, or some design flaw. (It can't be a glitch; it has to be a permanent
thing which prevents passing the grant.)
I suppose that's possible, but I can't see any othey way.
Noel
First, a minor correction:
> the M8264 Sack Timeout module ... there's next to nothing in print
> about them
There is also some coverage in EK-KD11E-TM-001, at: Section 4.7.2.4 "M8264
NO-SACK Timeout Module" (pg. 4-41, pg. 87 of the PDF), which I found while
looking for parity stuff (below).
> From: Fritz Mueller
> The KD11-E is pretty bare boned... Parity handling was also a quad "add on".
??? The KD11-E/EA doesn't do much with parity (below), so at first I thought
that maybe you were thinking of the M7850 Parity Controller (which is
actually a memory option, not KD11-E/EA specific; more below), but that's a
dual card.
The KD11-E/EA does not (like most PDP-11's) calculate parity; PDP-11 memory
units do all the work, and signal 'parity error detected' to the CPU over the
UNIBUS (using the PB line); the CPU will trap when it sees that (if enabled;
the KD11-E and -EA can disable recognition of parity errors, with jumpers).
See Section 4.7.2.7, "Parity Errors", in EK-KD11E-TM-001 (at pg. 4-45, pg. 91
of the PDF); the circuit diagram is on page K2-1 of the KD11-E/EA FMPS.
The M7850 has to be in the same backplane as the memory, but that can be a
different backplane from the one holding the CPU. So it can be 15' away, at
the other end of a UNIBUS cable.
Anyway, can you say more about the parity add-on?
>> So if i) a device requests a grant, and then drops the request at
>> _just_ the right time ... and ii) there's a break in that grant line
>> ... before it gets to the M9302, which can turn it around as a SACK ,
>> then ... the KD11-E CPU will hang!
> I believe a broken grant chain with an M9302 in place on the far side
> results in the grant being pulled up at the M9302, and then continuous
> assertion of SACK, hanging the processor straight out the gate.
Oh, right you are! (I'm glad _your_ brain is runed on - unlike mine! :-)
I happen to have an -11/04 (the -11/34's sibling) on the bench in my work
room, with one of Guy's very useful UA11's plugged into it. (BTW, the UA11:
http://www.shiresoft.com/products/ua11/Unibus%20Analyzer.html
is fantastically useful as a UNIBUS debugging tool. Everyone working on
UNIBUS machines should have one.) So I thought I'd go try an experiment.
It turned out to be a bit more complicated than I thought, but you're
basically right: a break in the grant lines (e.g. missing grant continuity
card) causes the downstream card to 'see' 'phantom' incoming grants (open TTL
inputs float high), and signal a grant on from there; and if there's an M9302
at the end of the bus, it will see that and jam SACK on.
The complication was that when I powered the machine on, it turned out that
something was asserting SACK when the machine was halted; if I put it into a
'BR .' loop, that goes away. I looked, and the KD11-D doesn't even _have_ a
SACK driver! So I tried un-plugging the KY11-LB, and the 'SACK on halt' went
away. (That machine has core, and I set the power-on vector to halt the
machine.)
Looking at the KY11-LB manual, it does in fact assert SACK (after it has sent
the KD11 a 'halt request, and receives a 'halt acknowledge'), to recognize
the CPU's acknowledgement of the halt request. (I have yet to check and see if
the KY11-LB asserts SACK if the CPU halts on its own accord - probably 'yes',
but that's a project for tomorrow.)
The thing that's puzzling me is that the M8264 seems to exactly replicate the
functionality of the M9302, with an 'unused' bus grant being turned into a
SACK. So I don't understand the point of the M8264. Whether the cause of the
grant is a rare timing window of a bus request being cancelled, or a broken
grant line; with an M9302 in the system, a SACK will result.
The only difference between the two is that because of the way grant lines
are wired, the M8264 will not respond to a broken grant line 'downstream' of
the M8264.
The M8264 does add this capability to a system using an M930 terminator - but
just switching to an M902 would be simpler. And the M9302 pre-dates the
M8264, as we can see from EK-11034-OP-PRE2. So I'm really quite confused as
to what the point of the M8264 was.
Noel
