> From: Jerry Weiss
> uNOTE # 028 indicates that MSV-11 JB/JC (M8637-B/C) doesn't do block
> mode.
I went and looked at uNOTE #28, after I found it (it's not in the initial set
of uNOTEs, but in the second set - the so-called 'OEM uNOTEs"; note that the
numbers were re-used between the two sets, so there are _two different_ uNOTE
#28's).
I couldn't find anything there about the JB/JC not doing block mode? All it
says is they "can not be used in a Q-BUS system due to gate array
incompatibilities".
Noel
> From: Chris Zach
> Just checked the configuration and block mode DMA *is* off.
Interesting. So it's not bklock-mode on the QBUS which is screwed up, but
normal QBUS transfers. That jibes with the comment abour "gate array
incompatibilities" (which I take to mean "errors" :-).
> was the 11/70's MASSBUS channels nothing more than RH11-C's attached to
> the old FASTBUS on the 11/45 cpu core (which is what an 11/70 really
> is, with cache) or did they port right to the memory box?
RH70's are totally different from RH11's - a hex card, and a couple of quads
- and the interface to the /70's memory system is totally different from the
RH11's (which goes to the UNIBUS):
https://gunkies.org/wiki/RH70_MASSBUS_controller
It has interfaces to both the cache, and the memory bus (although the diagram
in the 11/70 CPU handbook shows it as only connected to the cache).
I didn't follow the "the old FASTBUS on the 11/45 cpu core (which is what an
11/70 really is, with cache)"; the 70's cache is what's connected to what
used to be the FASTBUS, the memory bus connects to the cache, IIRC.
Noel
Hi friends,
Now that I have enough hobby time having quit my job two weeks before the
apocalypse, I'm interested in poking at my Kennedy 9800 tape controller
project.
I bought the tape unit in Q3 2017 and the seller said they had powered it
up and nothing seemed awry. I have not powered it up and reading about old
electrolytic cap issues I'm curious if I should do anything beyond replace
any obviously leaking/ruptured capacitors.
IIRC people have used a variac to gradually bring the power supply up to
operating voltage and somewhat refresh the capacitors - is this a thing? Is
this advisable?
Any help is appreciated!
--
Anders Nelson
www.erogear.com
> Date: Tue, 21 Apr 2020 16:17:07 -0400
> From: Chris Zach <cz at alembic.crystel.com>
> To: cctalk at classiccmp.org
> Subject: Re: pdp11/84 PMI memory: What is the problem with Q bus?
> Message-ID: <27647f0e-19d4-b484-d288-e9f3bb715363 at alembic.crystel.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Thanks Mark! Actually this was just the boards from the 11/84 (no idea
> what happened to the chassis, drat) so it's an 11/84 CPU (18mhz, FPP
> chip installed), 2 PMI boards (one old 2mb, one new 1mb) a console board
> of some sort and the Unibus map.
>
> I popped this into my BA23 to speed things up a bit in place of my quad
> height 11/73 CPU with 2mb memory. So far it seems to work, and with the
> CA memory in the PMI slot managed to boot RSX11M 4.2 and compile up EMPIRE.
Chris,
I understand now. I also have a PDP-11/83 in a BA123 box and the CPU and
PMI memory (M8637-E) can move from the Qbus box to the 11/84 box and work fine
In either. I spent a good bit of time tinkering with the 11/84 power supply which did not
Work until I put a M7556 minimum load module in it. Basically the +/- 12 Volts needs a
Load or you get a hung bus error. Also, with the Unibus you have to pay attention to
The NPR/NPG grant jumpers.
For disks on the QBus systems I used the UC07 and SCSI2SD. The UC07 can be
can be configured for block mode transfers and I think it is doing it. I guess I?d need
to hook up a logic analyzer to know for sure.
The 11/84 uses a UniBone and when it is emulating a MSCP disk, it can do 150
I/Os a second (using IOX on RSX11M+) The 11/83 using the UC07 and a SCSI2SD
Does about 60 I/Os per second. I think the UC07 could go faster but is limited by the
SDcard interface. I need to put a fast real SCSI disk on it sometime and see what it can do.
>
> My guess is the 11/84's Unibus talks directly to the PMI bus and
> orchestrates the data transfers, but there is something wrong when the
> PMI memory is accessed on the true Q bus. That would not happen on an
> 11/84 (CPU and Map use PMI only) but when you have a Q bus DMA device it
> probably manifests at random. It's possible the MTI card is throttling
> the DMA to single mode instead of hog mode, wonder if I want to screw up
> my disk to verify this?.
What is the model # for your MTI disk controller?
>
> Drat. On the positive side it's chock full of 256k chips, which I could
> pull off and put on the EA board to bring it up to 2mb memory. I have
> air heat tools and a pre-heater so getting the chips off should be
> pretty basic. Getting them on the new board though could be a pain since
> all the holes are soldered over?.
Moving the RAM chips sounds a bit tedious but would certainly be possible.
>
> No way to reprogram or fix it I assume?
Are you asking about making the M8637-B or -C into the -D or -E? If so I?ve
never seen any reference to doing that. I was very fortunate that the person
Who sold me the M8637-C was willing to trade it for a -E.
Mark
Guys,
I got a positive response about the Port-A-Punch cards so no longer any need
to respond to this one. Very encouraging.
Still looking for Jacquard cards and original Hollerith cards. Hope springs
eternal.
peter
|| | | | | | | | |
Peter Van Peborgh
62 St Mary's Rise
Writhlington Radstock
Somerset BA3 3PD
UK
01761 439 234
"Our times are in God's wise and loving hands"
|| | | | | | | | |
Hi all,
was just fishing in old memories & graphics systems. We had in the
1980's a big fridge from Grinnell Systems as a frame buffer on a 11/34.
Anybody remember those? Links to any documentation?
Cheers!
Back in 2013, Bob Rosenbloom asked:
> I have an HP 9872 plotter that just died. According to the internal self
> test (very nice!)
> one of the bib (MOS to TTL) drivers has failed.
Tony Duell wrote:
> the devie is very simple (it's simialr to the 74LS245) but the problem is
that one side of it does not work with TTL levels. It's a level shifter too.
Although the BIB functioned as a level shifter, in later devices using the
1818-2500 standalone 40-pin BPC Binary Processor Chip, including the 9872C
and 9872T, HP actually used the 74LS245 instead of the BIB. The only thing
they did to meet the MOS level input requirements of the BPC was to put a
10Kohm pullup resistor to +5V on each data line on the MOS side of the
buffer.
As noted elsewhere, the 74LS245 isn't pin compatible with the BIB, so an
adapter would be needed to substitute it.
The 9872A, which uses the BPC with the BIB chip, does not have pullups on
the MOS side. It also uses the HP 16-bit NMOS ROM directly on the MOS side,
and it's remotely possible that adding 10K pullups could be a problem with
the ROM.
I am on a mission to fix a bunch of power supplies and now I am looking at
my MicroVAX 3100/95. A few days ago I mentioned that the big smoothing
capacitors on the primary side might need replacing. I have done that now.
However, in doing so, I have discovered that *one* of the capacitors does
not get discharged after the power has gone off (this applies both to the
original ones and the brand-new replacements). Furthermore, after
discharging them with a resistor and checking that the charge had gone,
several hours later, the one that does not discharge, has some charge again,
that was not there before!
Does anyone know if these PSUs have a bleed resistor to discharge the
smoothing capacitors? Why would only one be discharged, is there normally
one bleed resistor per capacitor? Why would the capacitor acquire charge
again when it hasn't been powered on?
Thanks
Rob
Greetings
I went looking for a specific version of C-Kermit to reconstruct sources
for an old system (The Boston Software Works Venix for Rainbow that I
have). I didn't find the 4C(052) I was looking for, but did find many
previous 'presumed lost' versions.
https://bsdimp.blogspot.com/2020/04/finding-kermit-4x.html
has the details.
Of particular note: I got almost all the lost versions off DECUS tapes
hosted in various places because they were copies of the KERMIT tape,
pruned down to just be the DEC stuff. Maybe people here care, maybe not...
Warner
