Once again, I will be in the Bay Area from the 31st through the 4th
(actually morning of the 5th), and will be available to come over and
drool all over you collections. I will provide the 409 and paper
towels. Many of you have been very kind hosts before. Please email me
off list so we can set things up. I am also interest in that pizza
night things you guys do from time to time, if it is on.
--
Will
This is short notice, but things just may work out.
I will have my mostly empty van available to move computer stuff from
Seattle to the Bay Area, at a very nice reasonable rate (I need the
money for gas!). I can probably take a single six foot rack, as long
as it is not completely stuffed with equipment. That, or squatty
boxes, terminals, or anything else.
The catch is that the load up would have to be the early evening of
the 29th of this month - just a week away or so - and would need to be
pretty quick and easy, so no four hour jobs to get the things
uncovered and hauled out of your cellar. Load and go.
Unloading is far more flexible, as I will be in the Bay Area from the
30th through the 4th of May, and my days and evenings are mostly open.
I will not be able to take large things further than the San Luis
Obispo, or maybe Los Angeles with some arm twisting.
If interested, contact me NOW, and please include some details of the job.
--
Will
> I pointed out I';d jsut been thrown out of the library.
I am happy to say that nobody at any of the schools I attended would
have dreamed of throwing a student out of the library just because they
were there reading. Tony must have been particularly unfortunate.
And as far as Fred's experience with college admins go, thankfully I
don't think that kind of thing happens here. I would be surprised to
hear that it did.
I suppose I should be thankful to be where I am.
/Jonas
On 2011-04-16 19:00, cctech-request at classiccmp.org wrote:
> Are you saying that this uses a rack-and-pinion type of hard positioner?
> If so, it's the first one I've heard of in a floppy drive, but anyway...
It is indeed a rack-and-pinion positioner.
> You would want som way to eliminate the backlash between the rack and the
> drive gear. One common way to do thsi is to make the gear in 2 'slices'.
> One is fixed to the spidnle, the other is free to move by a small angle,
> but there;s a bias spring forcing it in a particualr direciton relative
> to the spindle. The idea is that said spring is pre-tensioned when the
> mechnaism is assembled so that the teeth of the 2 gears are forces to
> commpletel fill the gaps between the teeth on the rack.
I know what you mean. There is nothing like that here, everything is
probably too small. The pinion is about 2 mm diameter and the teeth on
the rack are something like 3 per mm...
> What I would do next is with the drive removed, try carefully moving the
> head back and forth and/or rotatign the stepper motor spindle and see
> what moves. If something is stripped then moving the head will not
> rotrate the motore and vice versa. Of course you may find that something
> is jammed solid, in which cae that could be the problem.
I removed the motor, it turns out the rack and the pinion is in good
shape. What I was seeing was just a deposit of grease and/or gunk. The
head assembly was locked solid. It runs on a steel rod approx. 2 mm
diameter which goes through what looks like bushes, and it was
completely jammed from lack of lubrication, dirt etc. The bad news is
that now everything is out of alignment since the head assembly came
loose when I was trying to move it (it was locked really, really solid),
and I don't have an alignment disk. Still, it was a learning experience...
I have ordered a new drive from a local shop, they don't keep them in
stock. They are only 6 Euros so replacing it will be a lot less trouble
than making it work again. I would have liked to fix it, but that is
simply not practical, sadly.
Interestingly, Atari drives are sold for about $50 on eBay, with
shipping to Sweden another $50. I suppose they are "collectable". That
works out at about 10x the price of a new one. The difference is that
the original drive is 720K and has a special bezel and eject knob, a new
one is 1.44M and the bezel and knob can be transferred from the old one.
The machine itself works with a 1.44M drive.
> > have a metalworking workshop with a lathe available to me:-) ).
> Also remember that if you dismantle the head poositioner, you will need to
> set the radial alignment, which needs an alignment disk. Something else
> you may well not have.
Indeed I don't... Next time, if there is one, I shall try squirting some
white spirit or something on to the guide rod with a syringe, carefully
work the head assembly loose and then lubricate the guide rod sparingly.
> While it certainly isn't worth getting a lathe and all the add-ons just
> to repair one floppy drive, it is somethign that you may want to consider
> at some point. Having the ability to make mechancial parts really
> increases the things you can repair, and it also removes worry from doing
> some jobs ('If I mangle this part getting it off, I can always turn
> another one.').
Yes, a lathe is a very useful machine. Unfortunately I can't really see
where to put one in my flat, except possibly a watchmaker's lathe. Of
course one of those would have been just the job here if I needed new parts.
/Jonas
Thanks for the suggestions so far. I tried a few things with the following to report:
I verified the copy of RT-11 on RX-01 floppy. It boots fine on the LSI-11 system it was built on, tried "BOOT RT11SJ" as well as with the "/FOREIGN" option and it ran fine on that system (which has an M7946 controller). The drive is configured for RX-01 mode only (since these are the only controllers I have in both Q-Bus and Unibus flavour).
Now, put that same drive on the 11/34 CPU with an M7846 card. Checked the CPU carefully: NPG jumpers are all intact on the backplane (CA1-CA2) and all unused slot D's have a grant continuity card. Just to ensure it works I reconfigured the console for 9600 baud (originally 300) and ran a simple "echo" program loaded at 001000 which runs fine (so it can store programs in memory and the execute them). The system has loads of memory - three cards with 16K, 48KW, and 96kW on them - so I did a quick check at locations 100000 and 700000 and memory is certainly there.
Tried typing-in the RX-01 bootstrap and running it: same as before, stops with "005134" on the display.
Added an M9301 card to avoid having to type-in the bootstrap each time (also, slot 3AB of my system was empty ... no terminator, nothing .... should have a terminator in that slot regardless and I should have added this card long ago). Now, I can just start the 11/34, and start the bootstrap ROM (with console emulator) at 773000. I get the four registers displayed as expected and the "$" prompt. Typed "DX0" to boot from the floppy. The heads engage and I can hear the heads stepping: Step, short pause, and three more steps, and then it halts again: "005134" on the display (when that address is examined, the contents are "000400").
Any further thought on how do diagnose this one would be appreciated!
Jerome: this is my personal "baby" which I have owned even before I went to engineering school. Now just part of a personal collection of interesting technology. I _had_ three RK-05 drives on the system at one point but those drives were stored very improperly and were completely destroyed (the system worked about 20 years ago with those drives and oddly, never had an M9301 installed - that slot was always empty). Now, I am just salvaging what was left working ... in my case I was very lucky that the CPU seems unscathed by the ravages of time! The RX-01 controller was picked-up a few years ago in the hopes I could make a basic system again with an RX-01 drive.
Cheers ... Mark
Professor Mark Csele, P.Eng.
Niagara College, Canada
300 Woodlawn Rd., L-23
Welland, ON, L3C 7L3
(905) 735-2211 x.7629
E-Mail: mcsele at niagarac.on.ca
URL: http://technology.niagarac.on.ca/people/mcsele
Author of "Fundamentals of Light Sources and Lasers", Wiley, 2004
Is anyone selling working mockups of early model PDP-11s?
Ie. something with console switches and blinkenlights that
runs a simulator or uses a fpga implementation of a PDP11
and interfaces to some modern hardware like SATA drive..
Have a friend looking for Multibus parts, told him I'd post here in
the hopes that someone here might be able to help it out. Here's his
request:
"I need an extender board for a system that uses a multibus backplane.
(Multibus I, MBI, whatever you want to call it) I have a system that
I need to work on and obviously need one of these to work on the
boards while they're in the unit.
Here's a link to a pic of one similar to what I need:
http://www.vectorelect.com/Product/Extenders/Multibus.htm
If anyone has one available, I'd be happy to hear about it and they
can email me at sexsymbol at execpc.com."
Marty
Nah, that subject line was just a teaser, Steve isn't coming to VCF East
-- this year -- but he does like our t-shirt! Check out this screen
capture of a Facebook exchange from just now:
http://www.snarc.net/woz2.jpg ..... come to VCF East and get your own!
(Irony: the VCF site is down tonight. Sellam is working to fix it pronto.)
