A friend who currently runs an PDP11 as part of his business had a failure of one of the PROMs in his disk/tape controller. These beasts seem to be unobtainium - does anyone have any spares in their kit or know of a source. Understand that the chips are one-time-programmable so pulls aren't a reasonable solution...
CRC
On Tue, 05 Apr 2011 11:33:39 -0700, "Chuck Guzis" <cclist at sydex.com> wrote:
> Jameco is still selling TPB24S81 PROMs:
??
> http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_27
> 828_-1
>
> Looks like a pretty close match. Of course, you have to find someone
> to program the darned things.
>
> --Chuck
Thanks for the link. I believe the N82S186 is the same chip. The bit rot extends to this biological entity because I now remember that I fought these nasties years ago in a different computer in a different universe.
On Tue, 05 Apr 2011 14:36:59 -0400, Dave McGuire <mcguire at neurotica.com> wrote:
> I can program them..
>
> -Dave
Thanks, but my trusty BC Micro can do the job. My first inclination, when asked to look at the problem, was that one of the bipolar ROMs had gone south. My friend had an identical SpectraLogic board that had died many years ago, but had the same configuration. We pulled the PROMs and did a compare to ensure that they tracked. One of the two hardware configuration PROMs read, but wouldn't self verify. Nor would it reprogram. Switching the good PROM from the failed board brought the system back up. We ducked this bullet, but getting a few spares in to go with our library of PROM content should help in the future.
Again, thanks for the help,
CRC
Lat week I asked about removing the potting compound from a 425E Network
block in a Western Electric 500 telephone. I have no successfully repaied
this unit, so I wil ldescribe what the problem was.
On my line simulator, the phone worked properly apart from the fact that
the microphone (mouthpiece, transmitter, whatever) didn't do anything.
Checks shows 0V between the terminals (its a carbon microphone, of
course, so you'd expect a standing DC votlag here). Also, the votlage
drop across the phone when off-hook (the simiulator provides a constant
line current) was much lower than I expected.
With thr telepghone unplugged, I could measure 22 Ohms (or so) between
the microhone cup contacts with the microhopne removed. The same
resistance was found between the R and B termainasl on the Netowork, even
with the wire on the B terminal disocnnected. And yet agai nthe same
resistance bwtween R and B witl all the wiring disconnectd from the Network.
There's a 22 Ohm resistor inside the Network with one end conencted to
the B terminal (and nothing else). Therefore I suspected a short from the
other end of this resistor to something connected to R.
at this point I decided to open up the Network, hence by posts last week.
After getting rid of that potting compound, I found tha, yes, the 'other'
end of that resistor did terst as a dead short to the R terminal. A bit of
careful inspection showed that one of the enamelled transformer wires
connected to the 22 ohm resistror passed over the lead of a 68 ohm
resistor conencted to R, and that there was a short there.
No, I didn't rewind the transformer. I desoldered the 68 Ohm ressitor
lead and put a bit of sleeving on it. Tests showed the resistances
between the Netowkr module terminals were now more reasonable, and after
reassmbling the phone it works fine.
Yes, I _could_ have bought a repalcement Netwrok block, but this is much
mroe fun :-)
-tony
Woot!
Some serious progress. In no particular order:
- Non-functional keyboard was traced to a (surprise) badly corroded stereo
phone jack. What threw me was that plugging in a straight Switchcraft
plug for continuity checking showed everything ending up where it should.
After I took off the side of the unit, I discovered that the right-angle
molded plug on the keyboard cable does not get inserted far enough to make
a reliable connection. This looks iffy even at best, but I'll start by
replacing the jack. By removing the daughterboard that carries it and
plugging the keyboard into it directly, the computer sees it. That's the
good news. The bad news is that (also surprise!) there are a lot of dead
keys. So perhaps I spoke too soon about it being intact. I have a Sun 4
keyboard on the way and will pick that for parts to get going quickly.
- Non-functional diskette drive was pilot error, but I don't think it was
on my part. There are two 20-pin ribbon cables leading into the drive
cage and the wrong one was plugged into the Lisa Lite controller board.
Hopefully that did not damage anything - it was like that when I opened
the unit! Plugged the correct cable in and it now tries to boot the
floppy.
I inserted the Lisa Test 3.0 disk 1 and it chugs away for a bit before
throwing a disk read error. Will try writing another copy on my mac,
since this one may have been damaged while working on the loading
mechanism.
I'm very surprised that so much appears operational given the horrible
state it arrived in. A testament to Apple's construction quality, for
sure.
Steve
--
Been doing some cleaning here, and going through my various DEC terminals. I've got a pretty good set going, but I'm missing the ever-elusive VT52 (OK, yes, and the VT-05, but that doesn't count. <grin>). The one that has managed to elude me for years, however, is the VT52. I know they made a lot of them - it was an early standard of sorts, but they don't turn up nearly as often as VT100's do.
So, anyone have one they'd be willing to sell me? I'm in NY, capital area. Working would be a plus, but complete is fine. I can usually fix things if all the parts are there.
Speaking of elusive... would also love to find a Tektronix 4010, but...
-Ian
> Although Oxford does not back me up on this, I was taught when younger
> that *heathens* belonged to no organized religion, though they often
> recognized (small) gods as influential in their lives. *Pagans*, on
> the other hand, engaged in formal worship of major gods (or a single
> non-Semitic-origin god), with organized priesthoods, etc. usw. k.t.l.
>
> The modern neo-pagans certainly fit the latter description. The Ya-Ya
> Sisterhood fits the former.
Considering the phrase "language is DEscriptive, not PREscriptive..."
In Neopagan and "New Age"/"New Thought" circles, Heathens are often those
who follow a ersatz reconstructionist tribal religion of the northern
European tribal cultures, often Scandanavian/Norse in origin (but not
exclusively, there are some more Germanic and Anglo/Saxon flavors as
well). Juxtaposition being "Pagan", which tends to (but not always) be a
slightly newer reconstructionist target (as in, the religion they are
attempting to reconstruct is often post-Roman but pre-Christian), so
consequently has a more cosmopolitain flavor, often integrating concepts
of deity and belief that would have not been present in northwestern
Europe (and in some cases are even Middle Eastern in origin).
That said, "pagan" and "heathen" have similar origins, so the words get
fuzzy. However, when talking about the various modern Neopagan religions,
people have their own perceptions that differ slightly from both the
classical and contemporary mainstream usage.
Gay Neopagan Fairy doesn't mean what a lot of "normal" people think. In
actuality, it's far far worse. Now, if you'll excuse me, I have to go
peathen.
We have a few spots left for exhibitors. So if anyone out there wants to register, then let me know ASAP.
We also have a few spots left for the hands-on workshops -- "Teletype 101" (in which you can win a good-condition model '33) and "Build your own transistor-logic circuit". Register for these via the "workshops" link at vintage.org/2011/east.
(Regular admission tickets are only sold at the door.)
Is there any interest in extending any of the PDP-11 operating systems
so that they are able to support dates at least until 3000? While my
personal interest lies with RT-11, I am curious if anyone has looked
at the requirements for any of the other PDP-11 operating systems
to determine what is required for Y3K date support? In addition,
are the resources (technical knowledge, files to make the required
changes and hardware to support the development) available?
For RT-11, the resources are available and I suggest a review of
the required software changes by anyone who has the technical
background to evaluate any proposals for Y3K implementation.
If other individuals who are interested in RSX-11, RSTS/E and
TSX-Plus are motivated to support Y3K implementation for
these OSs, I would be interested in providing support for
any solutions required to exchange dates between all PDP-11
operating systems.
I am not sure if there is any commercial impact to producing
Y3K code for PDP-11 OSs. However, it is possible that
any current commercial use MIGHT be more likely if Y3K
support is available. On the other hand, it is almost certain
that any Y3K projects for all PDP-11 OSs must be done
without any commercial support at this time. Consequently,
as with all DECUS contributions, any actual code changes
would become available to everyone. If this enhances the
commercial value of the PDP-11 OSs, then it should be a
positive development.
Responses and suggestions are appreciated.
If, as I have noted in the past there is no response, then at
some point when it seems worthwhile, I shall at least present
the technical details of what is required to implement Y3K for
RT-11. There may also be details of other enhancements along
with RT-11 bug fixes. If anyone has a wish list for RT-11 or
knows of any RT-11 bugs which need fixing, I would very much
appreciate the help.
Jerome Fine
