ity is that the motor has
failed, you can unplug the motor and apply 12 V to it and
see if it moves. Otherwise, the full-bridge driver has gone
bad. Or, mayvbe just a bad connection where the motor plugs
into the board.
Jon
it was the main computer resource on
campus. When the moved up to a 360/50, they were able to
benefit from multiprogramming, and got a boost in
throughput, although the 7094 was QUITE a bit faster than
the 360/50.
Jon
Sorry, I've lost track of the guy who was interested in
collecting CAMAC bits. Cleaning up our lab, I found a
Kinetic Systems 3922 Z1A crate controller, and
a 2926 Z1A ISA slot controller for it. Anybody interested?
Thanks,
Jon
On 3/18/23 04:34, Steve Malikoff via cctalk wrote:
G'day all,
I have just uploaded the engineering drawings for the early PDP-11/05, the
one with the solid (no slots) Mazak lower bezel
Huh? Mazak made machine tools. Did you mean Zamak
(zinc-based die casting alloy)?
Jon
On 3/18/23 15:48, Steve Malikoff via cctalk wrote:
Jon said
On 3/18/23 04:34, Steve Malikoff via cctalk wrote:
G'day all,
I have just uploaded the engineering drawings for the early PDP-11/05, the
one with the solid (no slots) Mazak lower bezel
Huh? Mazak made machine tools. Di
tinue
Paul's vision.
I guess Bill doesn't like old computers. Constant turnover
of newer machines sells a LOT of MS products.
Jon
you would see.
Jon
orted earlier!
Jon
wever. It is a
19" rack mount unit.
Jon
what the circuit looks like,
Well, in fact, it is impossible to make a transmission line
with such impedance. The impedance of free space is
supposed to be 277 Ohms, IIRC.
Jon
n it gets a narrow pulse to low, it will switch to
holding the line low. So, if you are using a Xilinx FPGA of
recent vintage, or some of their CPLDs, they will do exactly
this.
Jon
hen position using those coordinates. So,
anything that changes the reflection of the leads or causes
slight misalignment would cause an alignment failure.
Jon
pecifics of
certain family's pad options and how to deal with them in
pseudo-analog functions like crystal oscillators, switch
debounce, etc.
Jon
ng
iron. If a bridge develops, solder wick fixes it.
Jon
an X-acto knife to find
the ones that wiggle, and then touch up the soldering and
test again. With a BGA or leadless package, there's no easy
way to detect or fix bad soldering.
Jon
TTLE paste for the draw
the blob along trick to work.
Jon
plenty of room to
get your hands and tools under them. Generally from about
4-6". Then, it is a breeze to solder under the microscope.
Jon
ugh to fit even fairly
small through holes.
I've done well over 1000 boards with this system. Oh, and
most of it is RoHS, too.
Jon
7;ve
NEVER had one fall off when the top side was reflowed. The
solder almost certainly goes liquid again, but the surface
tension holds even this large part in place! The small
passives on the back will be held by surface tension for sure!
Jon
re formed AFTER plating to all sit on a flat
surface. If the leads have varying solder thickness after
removal, or are bent out of the seating plane by handling,
that will also affect the ability to reflow solder them
reliably.
Jon
it, and no peripherals. But, it did work.
Jon
x27;s amazing. I had no idea he was still around! I
hope he wrote up some memoirs or left stories.
Jon
to recover the files off this,
I'd be glad to donate the set. It appears to be 2 boxes of
floppies, 28 in total. I have some more floppies that seem
to be the last half of an earlier backup, with less info on
how it was written.
Thanks,
Jon
Pulse Engineering and Rhombus
Industries. I think DEC used Pulse Engineering in a lot of
PDP-11 and VAX vintage stuff, so maybe they used them back
in the PDP-8 days, too.
Jon
d wiring side with a shop
vac with a crevice tool. I really would not get it wet. If
you do this, vacuum all the water off and then dry in an
oven at 100F or so for a day. You can clean the card edge
fingers with an alcohol-soaked paper towel.
Jon
eft on long enough). I'd check that transistor for a
short, and then you can trace a few traces to identify the
primary terminals on the flyback and see if they are an open
circuit.
Jon
can't tell the trigger rate from looking
at the screen, but then they can see what happened BEFORE
the trigger event, and can freeze a single-shot event for
you to look at. The good Tek DPO scopes have not come down
enough to meet your price range (yet).
Jon
tronic loads.
The motor loads help balance it better, but the electronic
loads cause the generated leg to sag.
Jon
use a LOT of
power to run the 1403 printer.
Jon
On 05/01/2017 11:53 AM, dwight via cctalk wrote:
Aren't these water cooled?
I seem to remember hoses.
No, the 43xx series are all air-cooled. The 360/85 and
370/165 and 168 and 3033 series were water-cooled.
Cables the size of garden hoses, for sure, but no water.
Jon
It COULD be a bad
sensor, but is more likely to be a bad connection.
Jon
the VFD/filter and the
computers, so the line could be balanced around neutral, too.)
Jon
lation.
It isn't. See above. A lot of this is circulating current,
so the real power draw from the mains will be less. Still,
most likely over 10 real-power KW from your 240 V
single-phase mains.
Jon
Jon
t the file system is.
Jon
y got brighter) and then a
crowbar circuit tripped to shut it down. Unless you are
pretty skilled, switchers can be a bit hard to
troubleshoot. It might be easier to get a supply with the
needed voltages and just patch it in.
Jon
was
aimed at microwave/radar labs.
Jon
Bone Black, also about 3-5 W depending on CPU
load, but has a 1 GHz 32-bit RISC processor.
Definitely slower than a top of the line desktop, but
certainly usable.
Jon
a article on Dr. Wetterhahn seems to indicate
this went a lot slower than we were told in the seminar.
Not sure who to trust, there.
Jon
people who gave our seminar either
misremembered the situation or embellished it.
Still, pretty horrific situation when a highly skilled
person thinks they are doing everything right, and a couple
drops of something kills them.
Jon
lien URL format:
https://www.flickr.com/gp/smj_crash/4bgzj2
Auugh! My wife would kill me if she knew I was looking at
PORN on my computer!
Jon
ng right
within a larger system.
With VHDL, you generally do NOT work at the gate level.
Jon
th it is pretty slim).
Noel
Wow, what did they do with the boards???
Jon
both sides it makes a real mess
of the printed image.
Jon
ndow after the X and Y select
wires were in place.
Jon
he serial data
was at the correct level while the UART sampled the signal,
the rest could be garbage. But, how will a seriously
degraded channel ALWAYS pass the signal correctly just when
the UART samples it? NOT very likely.
Jon
ng glasses with logos on them. (Now, I know those are
fired onto the glass, so even more durable.) I have doubts
some kind of ink that could be printed by a print head could
be that durable.
Jon
ne
move. They had hundreds of boards, but I seem to recall
single-sided yellow paper-phenolic boards. I also thought
they used card-edge connectors, not Vari-Loc. I think they
started making these in about 1965 or so.
It has been a LONG time since I saw one of these.
Jon
mber of times.
The connectors are Elco Varilok.
Jon
t sweeping them off the
board, and clean up the pads with solder wick.
Takes maybe 2 minutes, and almost never damages the board.
Jon
well, and the parts generally fall off
the board when all leads are done, even on multi-layer
boards. The solder suckers that are used with a standard
iron are FAR inferior to the units described above.
Jon
complete computers!
Jon
ng I don't know how to do
right now is to open a memory window from the PRU to main
ARM memory to handle larger block sizes. But, I know others
have already done that.
Jon
uri vacuum generator that requires compressed air.
These work really well. I think the handpieces are model
SX-70.
Jon
r
stores popping up overnight like mushrooms, and disappearing
just about as fast.
Jon
On 07/13/2017 11:26 PM, jim stephens via cctalk wrote:
On 7/13/2017 6:52 PM, Jon Elson via cctalk wrote:
On 07/13/2017 11:02 AM, jim stephens via cctalk wrote:
On 7/13/2017 12:31 AM, Eric Smith via cctalk wrote:
There are also vacuum desoldering stations that use
"shop air" to
On 07/14/2017 11:24 AM, Chuck Guzis via cctalk wrote:
On 07/14/2017 09:00 AM, Jon Elson via cctalk wrote:
Hmmm, I really don't remember any such thing. I suspect that some
independent computer store chain got an OK to have a big Xerox logo out
on the front. That would be quite belie
said "Oh, it
needs floating point, it is too hard to recode our program!"
So, 50K down the drain! Geez!
Jon
check it out.
I thought that had closed a LONG time ago, but maybe they
have started it back up.
The original poster (Jon) had quite a nice pile as did I
as well, but those were days with a lot more
nice stuff than now. (70s)
Yeah, it is QUITE a pile, for sure. Still have my uVAX-II,
although
. AFAIK the nearest is OEM Parts in Colorado Springs. Maybe there's
something in Fort Collins.
Yup, sad, and these places were a big help to kids who were
interested in technology. Of course, with eBay, if you are
really interested in this stuff, you can still get your
hands on things.
Jon
r the paper size.
Jon
machine might be useful to
somebody wanting to read 7-track tapes.
I got a Pertec key to tape machine many years ago, and
extracted the tape drive section and turned it into a tape
drive for my Z-80 CP/M system. It helped immensely that the
Pertec came with complete schematics.
Jon
re not too different than that.
Jon
sed as a key to tape system.
Jon
ansfer drives, so ran the HECK out of
them at work (tape loaded and moving something like 100
hours a week.)
Jon
;t be said to be CLEARLY
wrong. It does look a bit odd, however.
Jon
comm format from the
ESS computer. The data rate was not real high.
But, there may have been other tape drives for other
purposes (firmware, diagnostics, etc.)
Jon
On 07/31/2017 03:13 AM, Alexandre Souza via cctalk wrote:
AFAIK, common household and vinegar and citric acid are the same thing. Can
you elaborate, please? O_O
Vinegar is Acetic acid, Citric acid is Citric acid, a
different chemical compound.
Jon
lights should glow very dimly. DEC put a resistor across
the transistor to put a slight warming current through the bulb. This
reduces shock to the filament every time it is turned on.
(This info is from other DEC machines, not PDP-8, but I'm pretty sure
they would do the same there.)
Jon
then it could be
a configuration issue (the plugged-in memory module is not
set at address zero, for instance) . But, eventually, you
would have to trace it through the prints. Fortunately, the
PDP-8 is not a terribly complex CPU.
Jon
drum memory!
Jon
some boot ROMs might not set this up right, but you
can always toggle in a boot program that handles it.
Jon
capacitors that
looked like they came from the 1950's or 60's. Black
tubular with color code stripes, and leads about 1/4" long.
Jon
every 5 years or so. The fix was to clean the fuse
clip with the finest sandpaper available and put in a new
fuse (even if you caught it before the fuse blew.)
Jon
x27;m selling, just to try and keep other people from
buying it.
If you have a PayPal account, you can just have them send
the required amount that way. You can even have PayPal
generate an invoice to them.
Jon
97190?_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D41376%26meid%3D9253420ebdf64d829d68079589c3d04a%26pid%3D19%26rk%3D1%26rkt%3D1%26sd%3D152665094101&_trksid=p2047675.c19.m1982
That must be a LAB-8, seriously cool! Currently $676, but I
suspect will go higher.
Jon
On 08/19/2017 11:29 AM, Rod Smallwood via cctalk wrote:
> Leaky Crowbar SCR?
>
Never heard of such a thing. SCRs are usually all the way
on, or all the way off. Why would it be sensitive to load on
the power supply?
Jon
the stupidest thing I've read today.
Yeah, my advice to Rod is "don't show your wife what you
wrote!" And, especially, don't show it to your DAUGHTER!
Jon
in Alabama for now.
Thanks,
Kyle
I have a working NEC Electra 16/32 at work, and the Electra
8/16 at home died last year and I replaced it with
and Asterisk system. I also inquired, and couldn't find
anyone that wanted spares. I suspect we may have the
LAST working NEC Electra.
Jon
re no card fingers on the CD card
edges, that would be a good sign it would be QCD only. If
it has ONLY the grant jumpers there, then it can work on a
normal Q bus slot.
Jon
stan. This TOTALLY removed the
slipping problem until the latex wore out.
Jon
plies mostly to 800 BPI NRZI. PE and GCR
are far less critical on this.
Jon
drive that is known to be in good calibration (both speed
and skew) is very helpful in standardizing drives.
Jon
, any
skew error would be doubled, This would be pretty annoying,
you'd have to write, turn around, check, adjust and then
repeat with the write step.
Jon
track" are, in fact, 7 track.
Kyread doesn't lie. Argh.
Time to try out the 7 track stack that Al sent me.
Ah, well, I can see why a 7 track tape won't read well on a
9-track drive!
Jon
On 09/11/2017 01:52 PM, shad via cctalk wrote:
leaded solder = AgPb alloy
Uh, no, that would be Silver-Lead. Regular old solder was
SnPb, that is Tin-Lead.
Jon
ace to get down to final length). -ethan
There's also LinuxCNC for machine control. ( linuxcnc.org )
Jon
20+ years ago, complete aftermarket power supply replacements for Apple ][ were
still available from Jameco and other suppliers. Maybe $40 ballpark.
Is that an MPS-40? I have an original Plus&Plus power
supply that I'm pretty sure was from an Apple ][ of some model.
Jon
ater ones
were CNC.
Jon
, explains why writes
are slower than reads even on spinning disks. Of course, if
you write entire tracks, it can just hold the partial data
until it has all the data for that track, and write out the
buffer in one rotation.
Jon
d you will not be able to
disassemble them.
Jon
g about original
AT's here, but mid-90's 386 and 486 systems.
I can only imagine a real AT would be even less likely to
handle a drive over about 40 MB.
Jon
work.) I
have some CDC Keystone (92185) drives.
Jon
On 09/29/2017 01:35 PM, Chuck Guzis via cctalk wrote:
On 09/29/2017 09:00 AM, Al Kossow via cctalk wrote:
On 9/29/17 8:48 AM, Jon Elson via cctalk wrote:
I did a few of these on a lathe years ago. It was a couple minutes job per
reel.
you are also going to have to cut holes near the hub
kew adjust screws on the head mount to
make it as straight as possible.
Jon
much
smaller wire to get the signal back up to what the read amps
need.
Jon
On 09/30/2017 10:31 PM, Chuck Guzis via cctalk wrote:
On 09/30/2017 06:29 PM, Jon Elson wrote:
Ahh, but the genius is built into the heads! Note that nobody
recorded 800 BPI on 7-track tapes. I think they supported 200 and 556
BPI, only. There were some low-density 9-track tapes, but
the
Diablo cartridge drive and larger ones that were essentially
plug-compatible IBM 2314-type drives were available in the
early 1970's. These had very little electronics
in the drive. A little bit of head seek logic and read and
write amps, that was about it.
Jon
art-up circuit involves a
high-resistance resistor and a small, low-voltage cap (16 -
25 V rating).
If either of those fails, the switcher will never start up.
Jon
difference between early IDE and SCSI drives. Several
hundred $ for a similar capacity drive.
Jon
gnals are pretty close to the signal names on
the tag cable for a selector channel.
I bought a Memorex 10 MB drive and SASI adaptor on an
introductory deal in a magazine. This was in about
1980-1982. I had it on my Z-80 CP/M system.
Jon
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