20 Nov
1998
20 Nov
'98
1:24 p.m.
At 18:46 11/20/98 +0000, you wrote:
The RL ribbon cable (from the RL11->bulkhead) can also be plugged in
backwards. At least the 'fault' lamp comes on if you do that, though...
Yes. On every DEC drive I own (and I guess most others), track 0 is at
the outside edge of the disk and the highest track is closest to the
I thought I should verify this. Seems sometimes when I assume something it
turns out wrong.
Thanks for the tips Tony!
I think I may get some time next week to get back to this project.
Regards, Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt(a)netsync.net
Member of Antique Wireless Association
URL: http://www.ggw.org/freenet/a/awa/
We all make mistakes (or at least I do :-)). It is
worth checking this.
Why DEC didn't use polarised connectors here is a mystery to me...
This is indeed a bone-headed thing DEC did. I bet a lot of field engineers
were cussing about that. Must have been two different design departments
between RK's and RL's (Allison. . . comments?) IIRC, the
RK07 spin-up is something like : Motor up to speed, brush cycle
(old drives only), positioner unlocks and moves to outer guard band,
postioner moves to spindle and back to track 0. Does yours do that?
Seems right recalling the several times I've watched this process on the
RK. I'll check for sure. Track 0 is at the outer edge I assume? spindle. Allison/Tim will now post a list of exceptions
:-)
No sure. And please don't think any of my messages are flames for lack of
knowledge (even if I write them late at night when I am not as awake as I
should be). _I_ had to learn all this stuff once, and I didn't have this
great list to turn to.
I certainly don't think any of your msgs are flames for ignorance as I know
you are the type who is willing to share his knowledge and teach others.
You did not get to the level you are simply by getting a book or two and
dumping it into your head :) It's experience in the good old School of
Hard Knocks, just like me (and I'm getting knocked about a little here:) )
Hmmm.. The
positioner would be on track 0 after a spinup, and the
standard boot is to read track 0, sector 0 into memory
and jump to the start of it. So you might not see any head movement if
there's nothing bootable on the pack.
I see. Of course with absolutely no prior knowledge of such details as this
I am completely oblivious to what should be what. Now is the time to learn. This is the first day ever of me even operating
an 11/34A. I'll have to
figure out from the rather terse instructions in the user's manual how to
find and examine registers. At least the Programmers Console has a variety
of good features for this.
Remember that on the PDP11, all I/O registers are just memory locations.
Halt the processor after the failed boot attempt, key in the first
address of the RK611 (I can't remember it, but you have the RK07 user
manual, don't you?) and then press Load Addr. Then press Examine
repeatedly and write down the octal numbers in the display. Convert to
binary and figure out what the bits mean from the user manual.
A couple of things to watch for. If you get a Bus Err on the first
'examine' then check you typed the address in right. If you did, then for
some reason the RK611 is not responding to the correct address.
If the Error bit is set in the appropriate RK611 register, then decoding
the other bits will give you a lot of info as to what happened.