OK, I confess it's been almost a day since I worked on my PDP-8/m. I
discovered that I appear to have, what looks to me at least to be, a very
serious problem. I thought that one of the LED's for showing the address
was out, been that way for at least a couple days. Then yesterday morning
I put it on the table I've been using when I'm working on it, and another
LED was out. Another address LED, but the one for the second bit, in other
words set it to address 0002 and it looks like you're at 0000, grrrr!
So I pulled the front off and discovered that the solder connections have
apparently gone bad. I reheated the solder, and added a little. That
fixed it for shortly longer than it took to get the front back on. The two
LEDs are back out.
Even more frustrating, checking out E46 on the G227 with my new TDS-220
Oscilliscope it looks as if everything is just fine. Yet the other day
when I checked it with the logic probe it wasn't (still have the same
problems with memory though). Probably better explain this, I'm seeing
'pulses' on the outputs that correspond to those on the E39 chip, in other
words one chip is doing the xxx0 - xxx3 and the other the xxx4 - xxx7,
which I wasn't seeing before. Still I really should recheck the results
with both the Logic Probe, AND the Oscilliscope.
So, I'm starting to wonder if I don't have some fairly serious problems
with the solder joints in this system. What is the best way to check for
this, and fix any problems that I find.
In any case I obviously need to get a decent soldering iron, the el-cheapo
Radio Shack one I've got is as old as some of the parts in the PDP-8! If
nothing else I need a decent tip.
Zane
| Zane H. Healy | UNIX Systems Adminstrator |
| healyzh(a)aracnet.com (primary) | Linux Enthusiast |
| healyzh(a)holonet.net (alternate) | Classic Computer Collector |
+----------------------------------+----------------------------+
| Empire of the Petal Throne and Traveller Role Playing, |
| and Zane's Computer Museum. |
| http://www.aracnet.com/~healyzh/ |
If everyone forwards the offending email to < abuse(a)hotmail.com > they'll
certainly claim it's a forged address unless it's real, in which case
they'll close his account immediately. They're a popular forged source,
though.
Dick
-----Original Message-----
From: Christian Fandt <cfandt(a)netsync.net>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Friday, December 03, 1999 8:30 PM
Subject: Re: Do You Have a Yen to be a Millionaire!
>Upon the date 03:21 PM 12/3/99 +0000, yen111opp(a)hotmail.com said something
>like:
>
> -- Snip rudely sent HTML --
>
>Well, at least they put a postal mailing address in this message. Maybe
>same outfit Bruce? Or has Hotmail become a 'hotbed' of spamming? I've got a
>yen to for certain not see them again ):-(
>
>--Chris
>-- --
Since there was significant interest in these scans (and to avoid hogging
our link to the net and incuring the wrath of my spouse) I have uploaded
the three pages of Ahl's book containing Super Star Trek to
www.litterbox.com/jim
Like the page says, they're quite large - around 2 megs each - in the intersts
of being OCR-able. (scanned at 300dpi) My page is very vanilla html, so
any old browser should work, including lynx.
--
Jim Strickland
jim(a)DIESPAMMERSCUMcalico.litterbox.com
-----------------------------------------------------------------------
BeOS Powered!
-----------------------------------------------------------------------
I would be interested also.
>===== Original Message From classiccmp(a)u.washington.edu =====
>Would the person who originally requested the David Ahl BASIC source for
>super star trek please e-mail me again? I've misplaced your e-mail. I have
>the scans ready to send. (actually, if anyone else wants copies of these
>scans, let me know and I'll mail them to you too. If there's enough interest
>I'll just stick them on my web page.
>
>--
>Jim Strickland
>jim(a)DIESPAMMERSCUMcalico.litterbox.com
>-----------------------------------------------------------------------
> BeOS Powered!
>-----------------------------------------------------------------------
On Dec 3, 20:19, Joe wrote:
> >I have a spool (1 lb?) sitting behind me of 96 SN silver solder, wasn't
> >"too" expensive and melts with a slightly hotter tip in my weller.
>
> That's the same kind of stuff that they sell here for soldering copper
> water pipes. NO LEAD ALLOWED! The last time I checked it costs about
> $16/pound. That's cheaper than good electrical solder.
Same here, at least for new installations. There are regulations about the
flux, too, I beleive.
> You have to watch out for any solder and make sure it's for electrical
> work. There are many other kinds of solder and many (most?) of them have
> acid fluxs. You can use it on electrical stuff but you'll be replacing
> everything in about six months!
Yes, most fluxes apart from rosin are at least mildly acidic, including
some electrical types -- you just have to ensure you wash them off properly
(and soon).
> That's an interesting idea. But I certain that you'd have to heat the
> joint to the melting pont of the old solder before this stuff would alloy
> with it. If that's the case then you could just take the part off then
and
> not go through all the rest of the procedure. I've mixed various lead
> alloys for casting bullets and you have to heat the mix to the melting
> point of the element with the highest melting point before they will all
> melt and alloy together. This is true even if the alloy has a lower MP
than
> the individual elements.
Curiously, that's not always the case, especially if you consider surface
effects. Solder actually sticks to a metal surface by forming a very thin
layer of an alloy with it. In effect, the solder dissolves the other metal
very slightly. That's partly why a copper soldering iron bit gradually
wears away even if you keep it well tinned, and partly why thin plain
copper cable that has tinned ends is weakest just at the point where the
tinning ends (the solder leaches away a tiny amount of copper, leaving the
wire slightly thinner just at the junction).
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
I sent a reply to that, but it didn't seem to hit the list.
printout on thermal paper.
kelly
In a message dated 12/3/99 6:47:50 PM Central Standard Time,
healyzh(a)aracnet.com writes:
> No, he's serious. I got a reply from him. The thing is one of us
> misunderstood what was being refered to, and I'm honestly not sure which of
> us misunderstood. I thought he was refering to OCRing papertape, he's
> talking about OCRing a printout of the source. The question is, is Kelly
> talking about a printout, or papertape?
>
> Zane
>
>
On Dec 3, 18:57, Allison J Parent wrote:
>
> <Dunno. But those DEC drives are rebadged Connors, and the Connor norm
was
>
> Only some are. Some are Seagate and others are DEC unique design. I
> believe the RZ56 is micropolus. However the one I'm holding does not say
> that.
My mistake :-( I know DEC bought drives from almost every manufacturer at
one time or another, but for some reason I thought the RZ56 was a Connor.
--
Pete Peter Turnbull
Dept. of Computer Science
University of York
-----Original Message-----
From: Zane H. Healy <healyzh(a)aracnet.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Friday, December 03, 1999 6:42 PM
Subject: Re: Basic Source for Super Star Trek
>You have OCR software for paper tape?
>
> Zane
>
Zane, He's kidding!!!!.. We tend to call that device an "optical paper tape
reader".. If you don't want to send it to the UK then I can help you out.
john
>>If you sent me a paper copy, I would be willing to scan it and run through
my
>>OCR software.
>>
>>john
>>
>>On Thu, Dec 02, 1999 at 09:51:41AM -0500, KFergason(a)aol.com wrote:
>>>
>>> I have a copy, on paper, of the HP2000F version.
>>>
>>> sttr1.bas
>>>
>>> Kelly
>>>
>>>
>>> In a message dated Wed, 1 Dec 1999 9:56:10 PM Eastern Standard Time, Al
>>>Kossow <aek(a)spies.com> writes:
>>>
>>> > "I do have the
>>> > original SPACWR.BAS (Mike Mayfield, converted by David Ahl, I think)
>>>if you
>>> > want that..."
>>> >
>>> > it would be nice to find the original HP2000 version somewhere. The
copy
>>> > that Jeff Moffatt has on the HP2100 page looks like a bad read.
>| Zane H. Healy | UNIX Systems Adminstrator |
>| healyzh(a)aracnet.com (primary) | Linux Enthusiast |
>| healyzh(a)holonet.net (alternate) | Classic Computer Collector |
>+----------------------------------+----------------------------+
>| Empire of the Petal Throne and Traveller Role Playing, |
>| and Zane's Computer Museum. |
>| http://www.aracnet.com/~healyzh/ |
>
>>> You're right. I meant to add that the solder that I'm using is a very
>>> low temperature solder with silver in it. 500 or 600 degrees would be too
>>> cold for standard solder. I love this silver stuff, it expensive but it
>>
>>Eh? Silver solder is certainly very nice, flows well, bonds to a lot of
>>metals,
>>etc., but isn't it usually _higher_ melting point? Conventional solder
> I don't know what the exact MP of this stuff is but my iron (Weller EC
>3000) is set to less than 600d and it melts and flows well at that
>temperature. I don't know if the temperature control is accurate or not
>though. This is 2% silver.
What is the rest of the solder? Tin, lead, something else?
"Silver solder" is an extremely vague term, covering everything from
special low melting point Indium-Silver alloys to 2% Silver/tin/lead
solders to brazing, depending on the context it is used in.
The indium-rich solders are *really* neat stuff, if you ever get a
chance to work with them. Melting temperatures down to near room temperature
are available, as well as entire series of solder alloys with graduated
melting temperatures for building up intricate assemblies. And many indium
solders will even wet and stick to *glass*.
Expensive stuff, as well!
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
