Date: Tue, 3 Jul 2012 23:53:51 -0400
From: Ethan Dicks <ethan.dicks at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Subject: Re: Modern computers with docs
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On Tue, Jul 3, 2012 at 10:33 PM, Jon Elson <elson at pico-systems.com> wrote:
> > The last machines I ever saw where schematics were available to the
> > end users were the VAX-11/780 and the uVAX-II. The 780 schematics
> > were as thick as a phone book and 11 x 17" pages. The uVAX-II
> > was a lot smaller, it was a hierarchical description, but gave a lot
> > of insight on how the processor and interface chips were organized.
>
The 11/750 and 11/730 also had full schematics and assembly drawings
on thick slabs of 11"x17" paper, accompanied by several 8.5"x11" tomes
of technical descriptions. I think even DEC stopped providing that
level of documentation in most cases after about 1983 or so.
I remember plenty of detailed Qbus docs but I don't remember running
across the uVAX-II printset. That would be interesting to review.
I have a KA-630 print set, if anyone in interested. Probably it should
be scanned
and archived with bitsavers. It is 11x17, and about 3/8" thick.
Jon
Hi,
This is a generic fixit for PowerPC Macs but always worth a try:
- Unplug the unit from the mains.
- Remove the NVRAM battery
- Leave to stand for *at least* 2-3 hours
- Power up
The issue is the NVRAM (referred to as PRAM on a Mac just to be
contrary) becomes corrupt as the battery runs down. If the machine has
been stood unused for a long time it may have this aforementioned
amnesia.
I have, however, heard a lot of sorry tales of PowerMac G5s suffering
all manner of weird problems with PSUs, leaking liquid coolers and
more. It's worth thoroughly checking the whole system over before
proceeding.
--
Mark Benson
http://markbenson.org/bloghttp://twitter.com/MDBenson
On 4 Jul 2012, at 09:37, Rob <robert at irrelevant.com> wrote:
>> There is a chance, I reckon, that the RasPi may end up like the IBM
>> PC. Quite respectably successful in its own right, but more important
>> for the whole market sector it spawned of enhanced-but-compatible
>
> I think that's actually the point!
Exactly. They aren't doing this for the profit, they are doing it for
the drive into the community and to get people programming as a hobby.
While yes I appreciate people have battered on about the documentation
being part under NDA and that sucks for driver development, really
that's not the part they are most interested in leveraging, they want
a small device that people, kids especially, can doodle about with
languages like C, Python etc on to get them enthused about creating
software in a modern context in order to inspire a new generation to
grow up with computer programming on the brain.
The project is at an early stage, really largely still late
development, but it's got the important thing - large amounts of
traction with the community and a friendly introductory price tag.
--
Mark Benson
http://markbenson.org/bloghttp://twitter.com/MDBenson
Date: Tue, 3 Jul 2012 14:19:58 -0700 (PDT)
From: David Griffith <dgriffi at cs.csubak.edu>
To: cctalk at classiccmp.org
Subject: IMSAI switch paddle replacements
Message-ID:
<alpine.DEB.2.00.1207031419440.9191 at sleipnir.cs.csubak.edu>
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Can someone point me to a source for replacement switch paddles for the
IMSAI 8080? Todd Fischer of imsai.net tells me that he has red ones, but
no blue ones left.
In this day of 3-d printers, maybe you can find somebody to print some.
You ought to
be able to get the ABS filament in blue.
Jon
Date: Mon, 2 Jul 2012 20:11:01 -0400
From: Michael Thompson <michael.99.thompson at gmail.com>
To: cctech <cctech at classiccmp.org>
Subject: Strange Core Memory Behavior in a PDP-8/L
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The RICM is still wrestling with the core in the PDP-8.
After replacing some diodes on the core stack we have all addresses
working.
We observed an interesting core memory behavior during our debugging
last Saturday.
We started the memory alignment procedure by looking at the
STROBE FIELD 0 signal and the amplifier output on pin E1 of the sense
amplifier. The STROBE signal was very late compared to Figure 5-6 in
the 8/L Maintenance Manual. We ran a short JMP loop and adjusted the
relationship with the trimpot on the M360 delay module. When we
halted the
processor and tried a examine core we only got just zeros.
We adjusted the M360 delay back where it was and single step worked
again. We found that the strobe-to-one-bit relationship was almost
100ns earlier when in single-step than it was with the processor
running. We checked the whole timing path from MEM START at pin N2 of
the M113 in slot C03, through all of the gates, delays, and
flip-flops, and found no timing difference between single-step and
running. Right now it looks like there is a 100ns delay difference
between the READ(1) signal that turns on the current in the core and
the bit signal showing up on the E1 pin of the sense amplifier when in
the single-step and running.
Is this normal behavior?
The first thing that comes to mind is one-shot recovery time. I might
guess that some
component has degraded, and the one-shot has a different delay when it
has been
recently triggered vs. when it has sat for a while. (I'm assuming a
classic 8, with
discrete transistors, not a later machine built with ICs.) Most
specifically, there probably
is a transistor that resets the capacitor at the end of the one-shot
cycle, and if that
transistor is weak, it may not get the cap fully discharged before the
next memory
cycle starts. Most core memories had circuits to adjust drive current based
on core plane temperature, maybe some adjusted timings as well. Also,
check for
dead decoupling capacitors, these could allow noise when running to alter
timings.
Jon
[I hope this is on-topic; I believe the machine is at least 20 years old]
I have a NEC Spinwriter 5525 printer that is available for the cost of
shipping (free if you pick it up). The printer is a wide carriage and
appears to have a RS232 serial interface. I do not know if the
printer works or not.
The machine is located in Langdon Alberta Canada (postal code is T0J
1X1) which is approximately 10 minutes east of Calgary.
The machine is rather heavy. I estimate 50 pounds or more. If there
is no interest, the machine is headed to the e-waste recycling.
I can send pictures upon request.
Contact by e mail:
i a m v i rt ihatespam u al @ @ @ g ma il . c om <-- remove
spaces and ihatespam
Thanks!
--barry
At 21:58 -0500 7/2/12, Cameron wrote:
>Fortunately they only made this assumption a few places, but figuring out
>what broke was maddeningly fiddly.
...and for the record, the resulting (I assume) TenFourFox rocks!
http://www.floodgap.com/software/tenfourfox/
There are multiple websites I use daily that load faster and better
on TenFourFox than on Safari on my PowerBookG4; the (on-topic) iMac
G3 is a no-contest win for it.
Cameron, thank you!
Anyone else surfing the web with a PowerPC Mac, I commend the above
site to your attention.
(no relation, just satisfied user).
--
- Mark 210-379-4635
-----------------------------------------------------------------------
Large Asteroids headed toward planets
inhabited by beings that don't have
technology adequate to stop them:
Think of it as Evolution in Fast-Forward.
> So, if there is someone out there that could pick these items up
> (Woodridge, IL - a southwest suburb), I would appreciate it. Time may
> be short. Please let me know offlist.
I just received a note saying this must be done today or tomorrow, as
the family departs on Wednesday!
--
Will
You never do know what you'll find on Craigslist. This time my bad
terminal habit gained another 200lbs of trouble with the acquisition
of two very interesting Teletype Model 40 CRT terminals, attractively
badged as the Bell System Dataspeed 40. The accompanying printer came
with them, as well as two very thick volumes of the Shop Manual for
these machines (which may be the same as what is already on Bitsavers
- I will check.) A very clean KSR33 Teletype was thrown in to round
out the deal. Here are the initial pics (shop manuals are stuck
somewhere in the car, will add them soon:)
https://picasaweb.google.com/102190732096693814506/TeletypePickup
Not much info out there on these terms. In fact, given the number of
labeled cards inside them, I'm not even sure they're strictly
terminals. I have read about local storage options, cluster
controllers and other peripherals which suggest that TT or Bell may
have tried to sell them as an office computing solution as well as
terminals. All I know is they are extremely heavy, probably thanks to
the massive PSUs in the bases. The CRTs slide off the two stalks in
the base, which contain the power and signal connectors. The
keyboards detach from the front of the base as well. Very modular,
novel design - and essential if one was to have any hope of lifting
these things.
The "printer" is only a shell. I thought at first it may have been
harvested for parts (I was told they came from the estate of a
deceased IL Bell repair instructor) but given the connections inside
the enclosure, I am wondering if it was designed to accept a standard
Teletype mech.
Of course, any knowledge out there that can be added here is appreciated.
(No I haven't powered them on yet...)
-j
--
silent700.blogspot.com
Retrocomputing and collecting in the Chicago area:
http://chiclassiccomp.org
