21 Jul
2000
21 Jul
'00
9:30 a.m.
Another useful piece of equipment is a multi-channel
logic analyzer. Most of these units can read out
pulse-timing directly, and will provide an invaluable
way to display TTL signal patterns and relationships.
Now, before anyone flames me, I will admit that
new versions of these can cost multiple thousands
of dollars, but I've noticed that a significant
number of older units are showing up at hamfests
for << $200. (I ran across a Tek. DAS analyzer at
the Trenton Computerfest for <$25.00)
These older units are becoming useless for
new and/or cutting-edge hardware development,
and are being dumped by a number of hardware
development firms, since most of them can't
sample systems with clocks > ~10-20 Mhz reliably,
but for the kind of antique-system tinkering most
of us do, these can be quite a help! The one thing
you should look out for when buying one is to
make _certain_ it comes with a set of test
pods/cables/probes. A podset can be impossible to
locate after the fact, and may cost you a horrendous
amount of cash if you try to order them from the
original manufacturer.
Also, I suggest that you stick to analyzers made by
larger companies such as HP and Textronix. You'll
have better luck finding docs and getting help
from other hobbyists that way.
-al-
-acorda(a)1bigred.com
-----Original Message-----
From: allisonp(a)world.std.com [mailto:allisonp@world.std.com]
Sent: Friday, July 21, 2000 1:17 PM
To: classiccmp(a)classiccmp.org
Subject: Re: Scope use...
hi,
think of an oscope as a graphic voltmeter that plota against time.
the X axis is volts and Y axis is time.
That is along way from troubleshooting with one. To trouble
shoot with one
you really need to have some idea of waht you can expect to
see vs what
you actually saw. Most prints do not automatically give you that.
While a scope is handy, for fixing machines that were
formerly working a
DMM and logic probe tend to be more useful. Exceptions exist
like setting
hammer flight time on charaband printers or slice levels and
timing for
older core stacks. The latter being adjustments rather than
fixed by rules
of logic.
Allison
On Fri, 21 Jul 2000, Bill Sudbrink wrote:
I was going to post this request sometime, John
Fousts
post has inspired me to do it now. Anyway, I have also
recently acquired an oscilloscope (Tektronix TDS 3012)
and, while I have all the documentation and some notion
of what an oscilloscope does, I really don't know how to
bring it to bare against the several dead/flakey systems
currently in my possession. I hope this message will
start a "how to use an oscilloscope to diagnose vintage
hardware problems" thread.
Thanks,
Bill
(by the way... bills(a)adrenaline.com is now my email address)
21 Jul
21 Jul
9:47 a.m.
I'll second that. I picked up a used HP 16xx something or other with 4
pods of 8 inputs each, and it's been so useful debugging my home
designs. An alternative would be a PC parallel port based model, but
they seem kind of cheesy compared to a nice, solid, HP unit.
I paid less than $200 as I recall - probably just worth it for all the
microclips,
Ryan
Corda Albert J DLVA wrote:
Another useful piece of equipment is a multi-channel
logic analyzer. Most of these units can read out
pulse-timing directly, and will provide an invaluable
way to display TTL signal patterns and relationships.
10:45 a.m.
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3:08 p.m.
You're right, Tony, many of them are cheap because they're incomplete. I
paid over $1k for mine, but it was complete, right down to the manuals and
GPIB/RS232/Epson Printer adapters. It also came with ROM packes and
self-test jumpers.
I've seen plenty of LA's without these, and even a number of
pods/lead-bundles without the LA, in each case worth little without the
"other-half." I wonder why surplus dealers let this happen? They'd get
10x
the money if the equipment were complete.
Dick
----- Original Message -----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, July 21, 2000 1:45 PM
Subject: Re: Other useful test equipment (was: RE: Scope use...)
instrument.
Another useful piece of equipment is a multi-channel
logic analyzer. Most of these units can read out
Agreed. My Logic Analysers get a _lot_ of use.
Now, before anyone flames me, I will admit
that
new versions of these can cost multiple thousands
of dollars, but I've noticed that a significant
number of older units are showing up at hamfests
for << $200. (I ran across a Tek. DAS analyzer at
the Trenton Computerfest for <$25.00)
I picked up an old Gould unit for \pounds 55.00 over here. It's 16
channels, 100 MHz.
One thing, make sure the pods/probes are with it. These probes are
'active' -- they include a high speed comparator circuit. They're
expensive to buy (if they're available at all!), and non-trivial to
build. They're also specific to a particular model (or range of models)
of analyser.
Mine was _missing_ the probes (probably why it was cheap). Fortunately
there was a service manual with it, and I discovered that the inputs to
the analyser were differential ECL signals. I made something using 10124
(TTL-ECL translator chips) that gives me TTL inputs (which is all I ever
need), but I don't get the fun-but-useless-most-of-the-time variable
thresholds mentioned in the manual.
These older units are becoming useless for
new and/or cutting-edge hardware development,
and are being dumped by a number of hardware
development firms, since most of them can't
sample systems with clocks > ~10-20 Mhz reliably,
There are some reasonable 100MHz instruments out there which aren't _too_
expensive. Those are easily good enough for any classic computer repair.
And don't feel that because the master clock on the PCB-in-question is
100MHz or something of that order that a 100MHz (or even slower) analyser
is no use to you. There's a lot you can test even with a slower
Some instruments will are designed to sample faster if you use fewer
channels (perhaps 16 channels at 25 MHz, 4 channels at 100MHz --
obviously they load the 4 channels into 4 shift registers and read them
out in parallel (16 bits) every 40ns. Not as nice as a true 100MHz
analyser, but better than nothing. This trick _can_ be used externally to
'push' an anlyser that's too slow for the circuit-under-test, but it's a
bit of a fiddle to get working properly.
Modern analysers have all sorts of fancy display modes (for example they
can be connected to a CPU bus and they'll display a disassembly of the
code that's being executed). But that, IMHO, is secondary to getting the
data in the first place. If you can read in the bits, you can figure out
what they mean later. Even older analysers often have a IEEE488 (or maybe
RS232) port so you can link them to a computer to interpret the data.
Also, I suggest that you stick to analyzers
made by
larger companies such as HP and Textronix. You'll
Gould/Biomation is another one to look for.
-tony
4:52 p.m.
Upon the date 06:08 PM 7/21/00 -0600, Richard Erlacher said something like:
You're right, Tony, many of them are cheap because
they're incomplete. I
paid over $1k for mine, but it was complete, right down to the manuals and
GPIB/RS232/Epson Printer adapters. It also came with ROM packes and
self-test jumpers.
I've seen plenty of LA's without these, and even a number of
pods/lead-bundles without the LA, in each case worth little without the
"other-half." I wonder why surplus dealers let this happen? They'd get
10x
the money if the equipment were complete.
It happens many times because the dealer ends up buying a pallet, or
somesuch lot of gear, that is simply randomly grabbed and tossed into one
of several piles at the company getting rid of same. Such company simply is
dumping obsolete gear to get it off its books and can care less about what
goes with what. And with bankruptcys or plant closures, a third-party
outfit such as an auditing/accounting firm is sometimes contracted to clean
out a company and they have little time, technical ability or inclination
to organize sets of test gear. One part of this 'thing' is on pallet 'A'
while another important part is on pallet 'B', or even way over on 'X'.
Been there, seen that >:-(
Regards, Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt(a)netsync.net
Member of Antique Wireless Association
URL: http://www.antiquewireless.org/
8:36 p.m.
Oddly enough, I've seen several complete analyzers sold in separate lots,
all held by the same dealer, but he wasn't thorough enough to notice that he
had the whole deal.
I bouth a spare pod for my 1240 there, though I haven't needed one. He had
seven pods, just as I had, though I now have a spare. That means I have
then entire set of equipment available for the thing. Frankly, though I'm
moderately adept at using it, by now, I still have a long way to go to
exploit the instrument fully. Unfortunately, he didn't have the pods when
the analyzer was there, and his was a 1241 (color) rather than my mono
version, and sold the analyzer for $150, and the pods for $5 each. When I
showed him the lead sets, he indicated he though that he had them, but
hadn't run across them yet. ... sad ...
Dick
----- Original Message -----
From: Christian Fandt <cfandt(a)netsync.net>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, July 21, 2000 7:52 PM
Subject: Re: Other useful test equipment (was: RE: Scope use...)
is
Upon the date 06:08 PM 7/21/00 -0600, Richard Erlacher
said something
like:
>You're right, Tony, many of them are cheap
because they're incomplete. I
>paid over $1k for mine, but it was complete, right down to the manuals
and
>GPIB/RS232/Epson Printer adapters. It also came
with ROM packes and
>self-test jumpers.
>
>I've seen plenty of LA's without these, and even a number of
>pods/lead-bundles without the LA, in each case worth little without the
>"other-half." I wonder why surplus dealers let this happen? They'd
get
10x
the money if
the equipment were complete.
It happens many times because the dealer ends up buying a pallet, or
somesuch lot of gear, that is simply randomly grabbed and tossed into one
of several piles at the company getting rid of same. Such company simply dumping obsolete gear to get it off its books and can
care less about what
goes with what. And with bankruptcys or plant closures, a third-party
outfit such as an auditing/accounting firm is sometimes contracted to
clean
out a company and they have little time, technical
ability or inclination
to organize sets of test gear. One part of this 'thing' is on pallet 'A'
while another important part is on pallet 'B', or even way over on 'X'.
Been there, seen that
Regards, Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA cfandt(a)netsync.net
Member of Antique Wireless Association
URL: http://www.antiquewireless.org/
8:25 p.m.
New subject: MiniScribe 3412 jumper settings needed
Hello,
Anyone have information on what the nine jumper settings are? I've
searched but didn't come up with anything other than hd/cyl/sec
everywhere.
Bill Dawson
<mailto:whdawson*at*mlynk.com> <- Anti-spam protection
?
Your computer will do far more than you ever expected it to,
and that won't be enough.
Pournelle's First Law
22 Jul
22 Jul
5:17 a.m.
New subject: MiniScribe 3412 jumper settings needed
On Sat, 22 Jul 2000, Bill Dawson wrote:
Anyone have information on what the nine jumper
settings are? I've
searched but didn't come up with anything other than hd/cyl/sec
everywhere.
Check the Hardware Resources section of the VCF Link Library:
http://www.vintage.org/cgi-bin/links.pl#hardware
There are a couple hard drive databases in there.
Sellam International Man of Intrigue and Danger
------------------------------------------------------------------------------
Looking for a six in a pile of nines...
VCF 4.0 is September 30-October 1
San Jose Convention Center, San Jose, California
See http://www.vintage.org for details!
12:08 p.m.
New subject: ISC 8000 Series brochures for postage.
Anyone want 2, 4 page colour brochures on the 8000 series of Intecolor
computers. These are the first PCs ya know :)
First come basis. Please reply directly to me.
Kevin Stumpf - The Nostalgic Technophile - Unusual Systems
www.nostalgictechnophile.com - 519.744.2900 EST/EDT (GMT - 5)
12:11 p.m.
New subject: Early wp file translators for trade.
Anyone want Swap and Perfect Exchange. Swap handles Wordperfect, Multimate,
Wordstar, and Displaywrite. Perfect Exchanges goes between Wordperfect and
"13 other wp packages." In original packaging. 5 1/4" diskettes (of
course).
I would like to trade for a book from the 1960s about computing or a DEC
handbook.
Please reply directly to me.
Kevin Stumpf - The Nostalgic Technophile - Unusual Systems
www.nostalgictechnophile.com - 519.744.2900 EST/EDT (GMT - 5)
21 Jul
21 Jul
2:57 p.m.
You'll get no flame from me, since I bought one (TEK 1240) about ten years
back, and have never regretted it, though I've seldom had to use it.
It's quite straightworward to make your own PC-based logic analyzer. I even
have a 20-year-old PCB for a multiplexer that displays each of eight traces
in sequence, with a fixed voltage offset between them. This was publushed
in "PopTronics" back in the '70's. These are pretty handy, but with
srams
as cheap as they are today, an all-digital version would be quite easy to
build.
What's tricky, however, is knowing when you're done with the trigger
circuit. Triggering is a major issue with logic analyzers, particularly
with wide and not-so deep sample buffers. It may take a week to specify the
trigger spec correctly, yet it takes only a second to use it, followed by a
week of poring over the resulting data. Building all the desired features
into a single circuit is not an easy trick, however.
Back in '80 or so I needed a very wide LA, wider than what I could afford at
the time, so I built one with the 384-bit width that was required. It was
no picnic! Today's ultra-fast CPLD's lend themselves to building the fast
and wide samplers that are such a pain to build with TTL. These can capture
data at 200+ MHz and feed the 8-bit assembled bytes into an sram with little
or no pain.
It might be interesting to revisit such a problem. An old '486 PC dedicated
to that function would almost be worthwhile . . .
Dick
Dick
----- Original Message -----
From: Corda Albert J DLVA <CordaAJ(a)nswc.navy.mil>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, July 21, 2000 12:30 PM
Subject: Other useful test equipment (was: RE: Scope use...)
Another useful piece of equipment is a multi-channel
logic analyzer. Most of these units can read out
pulse-timing directly, and will provide an invaluable
way to display TTL signal patterns and relationships.
Now, before anyone flames me, I will admit that
new versions of these can cost multiple thousands
of dollars, but I've noticed that a significant
number of older units are showing up at hamfests
for << $200. (I ran across a Tek. DAS analyzer at
the Trenton Computerfest for <$25.00)
These older units are becoming useless for
new and/or cutting-edge hardware development,
and are being dumped by a number of hardware
development firms, since most of them can't
sample systems with clocks > ~10-20 Mhz reliably,
but for the kind of antique-system tinkering most
of us do, these can be quite a help! The one thing
you should look out for when buying one is to
make _certain_ it comes with a set of test
pods/cables/probes. A podset can be impossible to
locate after the fact, and may cost you a horrendous
amount of cash if you try to order them from the
original manufacturer.
Also, I suggest that you stick to analyzers made by
larger companies such as HP and Textronix. You'll
have better luck finding docs and getting help
from other hobbyists that way.
-al-
-acorda(a)1bigred.com
-----Original Message-----
From: allisonp(a)world.std.com [mailto:allisonp@world.std.com]
Sent: Friday, July 21, 2000 1:17 PM
To: classiccmp(a)classiccmp.org
Subject: Re: Scope use...
hi,
think of an oscope as a graphic voltmeter that plota against time.
the X axis is volts and Y axis is time.
That is along way from troubleshooting with one. To trouble
shoot with one
you really need to have some idea of waht you can expect to
see vs what
you actually saw. Most prints do not automatically give you that.
While a scope is handy, for fixing machines that were
formerly working a
DMM and logic probe tend to be more useful. Exceptions exist
like setting
hammer flight time on charaband printers or slice levels and
timing for
older core stacks. The latter being adjustments rather than
fixed by rules
of logic.
Allison
On Fri, 21 Jul 2000, Bill Sudbrink wrote:
I was going to post this request sometime, John
Fousts
post has inspired me to do it now. Anyway, I have also
recently acquired an oscilloscope (Tektronix TDS 3012)
and, while I have all the documentation and some notion
of what an oscilloscope does, I really don't know how to
bring it to bare against the several dead/flakey systems
currently in my possession. I hope this message will
start a "how to use an oscilloscope to diagnose vintage
hardware problems" thread.
Thanks,
Bill
(by the way... bills(a)adrenaline.com is now my email address)
11:20 a.m.
Date: Fri, 21 Jul 2000 17:57:51 -0600
From: Richard Erlacher <richard(a)idcomm.com>
Subject: Re: Other useful test equipment (was: RE: Scope use...)
To: classiccmp(a)classiccmp.org
Reply-to: classiccmp(a)classiccmp.org
Back in '80 or so I needed a very wide LA, wider
than what I could afford at
the time, so I built one with the 384-bit width that was required. It was
no picnic!
384bits to log? Whew, that would be big PCB with under a hundred
ttl ICs or so and tons of sram ics. What was that needed to do that
logging and what was that project under test hooked up by that
oddball 384bits logger?
It might be interesting to revisit such a problem. An old '486 PC dedicated
to that function would almost be worthwhile . . .
What is your propseal logger for this 486 pc idea? I have several.
:-)
Dick
Wizard
4:48 p.m.
That thing was built on several Multibus-I cards with LOTS of parts. Each
channel was sampled with a 4-bit shift-register that fed a half an 8-bit
register and a 4kx4 SRAM (55ns, which, for a 16Kb sram was considered very
fast). The whole thing was over 1100 IC's on 12 cards in three
interconnected MULTIBUS cardcages plus a display circuit and a CPU for
interacting with the "console" terminal port and driving the various
controls. It made me regret I never built a Multibus-I wirewrap card of my
own and to my standards. That would have saved a few cards.
The system was intended for monitoring VME bus signals plus various
additional channel signals for a test system. It was a major pain and I'm
glad I've by now forgotten more than I remember about it. I got the thing
to work failrly well, but by that time had much better ideas for a
2nd-generation device which I was never able to get someone to pay me to
build. I did, however, build VME wire-wrap cards, capable of supporting the
at-that-time relatively new IDC ribbon cable connectors most other cards
wouldn't. It also allowed the use of PGA parts without a multi-K-buck
adapter.
I know a lot more about sampling circuits than I ever wanted to know, yet
still don't think I'd like to build a LA without someone else specifying the
triggering modes. I'd go on forever trying to figure out what was needed
and what was just a whim.
Dick
----- Original Message -----
From: <jpero(a)sympatico.ca>
To: <classiccmp(a)classiccmp.org>
Sent: Friday, July 21, 2000 2:20 PM
Subject: Re: Other useful test equipment (was: RE: Scope use...)
afford
at
dedicated
Date:
Fri, 21 Jul 2000 17:57:51 -0600
From: Richard Erlacher <richard(a)idcomm.com>
Subject: Re: Other useful test equipment (was: RE: Scope use...)
To: classiccmp(a)classiccmp.org
Reply-to: classiccmp(a)classiccmp.org
> Back in '80 or so I needed a very wide LA, wider than what I could > the time, so I built one with the 384-bit width
that was required. It
was
no picnic!
384bits to log? Whew, that would be big PCB with under a hundred
ttl ICs or so and tons of sram ics. What was that needed to do that
logging and what was that project under test hooked up by that
oddball 384bits logger?
>
> It might be interesting to revisit such a problem. An old '486 PC
to that
function would almost be worthwhile . . .
What is your propseal logger for this 486 pc idea? I have several.
:-)
Dick
Wizard
4:48 p.m.
Another useful piece of equipment is a multi-channel
logic analyzer. Most of these units can read out
pulse-timing directly, and will provide an invaluable
way to display TTL signal patterns and relationships.
[...]
Also, I suggest that you stick to analyzers made by
larger companies such as HP and Textronix. You'll
have better luck finding docs and getting help
from other hobbyists that way.
If you can afford them, the HP 1650, 1660, and 1670 series are good
standalone analyzers. They are based on the same technology as the
16500 series analyzer mainframes.
However, it is much more common to find the older 1630 and 1631
analyzers for reasonable prices. They can do 25 MHz state analysis and
up to 16 channels of 100 MHz timing analysis. (State analysis collects
samples synchronous to the edge on an externally supplied clock, while
timing uses an internally generated clock.) They have an HP-IB (IEEE-488)
interface for computer control.
The 1631 models add a 2-channel 200 megasample/second 50 MHz digital
oscilliscope.
max max
state timing digital
model channels channels pods scope recent ebay prices
1630A 35 8 4 no
1630D 43 16 5 no $200, $61
1630G 65 16 7 no $200.50
1631A 35 8 4 yes
1631D 43 16 5 yes $460, $300, $395,
(Note that there is no 1631G; the same backplane slot is used for EITHER
the extra analyzer channels OR the oscilliscope.)
Make sure you get pods and leadsets; derate the prices accordingly if
those are missing. It's possible to make your own leadsets, but you
*need* the pods, as they contain active electronics.
8767
days inactive
8768
days old
13 comments
10 participants
participants (10)
-
ard＠p850ug1.demon.co.uk -
cfandt＠netsync.net -
CordaAJ＠nswc.navy.mil -
eric＠brouhaha.com -
foo＠siconic.com -
jpero＠sympatico.ca -
kstumpf＠unusual.on.ca -
richard＠idcomm.com -
ryan＠inc.net -
whdawson＠mlynk.com