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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Time sink!
      #419718 - 12/23/15 07:13 PM

Ran across this blog that details some repairs made to a IBM 1401 - a 50 years old main frame computer.

Qui-binary arithmetic, anyone?


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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
Time sink! [Re: Russell Holton]
      #419731 - 12/23/15 10:10 PM

Russell, the IBM 1401 was first produced in 1959. When production ceased in
1971, 12,000 had been produced. The original forecast was for about 100.

During the early 1960s I managed the development of a bunch of its system
programs -- Autocoder, RPG, IOCS, FORTRAN, COBOL and Sort. It was a
wonderful machine. We used to debug our programs running a 1401 emulator on
the IBM 701 and 704 because there were a lot more of them available at the
time than 1401s.


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Ray Tackett
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Reged: 04/30/04
Posts: 8892
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Time sink! [Re: Russell Holton]
      #419732 - 12/23/15 10:18 PM

Whee! I was teaching parts of that stuff, mainly error detection and
correction using Hamming code, to graduate students in the late 1980s. IMO
it's still a neat example of fun things you can do with mathematics.

The Wikipedia article:

https://en.wikipedia.org/wiki/Hamming_code

is way too narrow in scope. It discusses only telecommunications, where I
have never seen a Hamming code used. I saw it in very large (for the day)
memory arrays which used hundreds of not-so-reliable 1, 2, or 4Kbit DRAM
chips.

--------------------
Ray,

Owner, Lake Wood Be Gone

Turning quality lumber into sawdust and noise since 2013.


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Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Time sink! [Re: Ray Tackett]
      #419745 - 12/24/15 05:48 AM

Quote:

The Wikipedia article:

https://en.wikipedia.org/wiki/Hamming_code

is way too narrow in scope. It discusses only telecommunications, where I have never seen a Hamming code used. I saw it in very large (for the day) memory arrays which used hundreds of not-so-reliable 1, 2, or 4Kbit DRAM chips.




Then edit the article and add your knowledge. :)

--------------------
Terry
Mostly 0W3


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Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Time sink! [Re: Ward Miller POU-NY]
      #419746 - 12/24/15 05:50 AM

Quote:

Russell, the IBM 1401 was first produced in 1959. When production ceased in 1971, 12,000 had been produced. The original forecast was for about 100.




Didn't the head of IBM one time state that he figured the world market for computers was something like 8?

Oh, here is the wiki quote:

Quote:

Although Watson is well known for his alleged 1943 statement, "I think there is a world market for maybe five computers," there is scant evidence he made it.




--------------------
Terry
Mostly 0W3


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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Time sink! [Re: Terry Carraway]
      #419758 - 12/24/15 12:49 PM

Quote:

Quote:

Although Watson is well known for his alleged 1943 statement, "I think there is a world market for maybe five computers," there is scant evidence he made it.







Given the cost to buy and operate a 1940's computer, he might have well have been right.

As I recall, IBM was formed to help the government tabulate the US Census. One of the jobs of the early computers was to create the ballistics table for firing big guns. Then there was the one built for code-breaking. All-in-all, applications that only first world governments would have or be able to afford.

But once they got cheap and powerful enough to do business accounting, the market suddenly got much, much larger. And with shrinking size, costs and increasing power, we've entered an era that even the science-fiction writers got wrong. Notice the difference in computers between the original Star Trek series (essentially a tabulator) and the later ones (with a holodeck).

Here's an illustration of the power of today's computers:

Quote:

Could an IBM mainframe from the 1960s mine Bitcoin? The idea seemed crazy, so I decided to find out. I implemented the Bitcoin hash algorithm in assembly code for the IBM 1401 and tested it on a working vintage mainframe. It turns out that this computer could mine, but so slowly it would take more than the lifetime of the universe to successfully mine a block. While modern hardware can compute billions of hashes per second, the 1401 takes 80 seconds to compute a single hash. This illustrates the improvement of computer performance in the past decades, most famously described by Moore's Law.




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Ralph Jones
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Re: Time sink! [Re: Russell Holton]
      #419763 - 12/24/15 02:01 PM

I like to speculate on what Richard Feynman could have done in 1944 with an Apple II...

--------------------
Ralph Jones
LS-4a N49LS 6R


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Ward Miller POU-NY
Top Gun


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Posts: 10508
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Time sink! [Re: Russell Holton]
      #419783 - 12/24/15 05:36 PM

Russell, the IBM 1401 we're talking about here had 1.4K memory in the
engineering model. The first ones delivered to customers had 4K and had
punched card input and output. A year later they shipped 8K versions, then
12K. Eventually, the largest was 16K.

With all that, we learned to write pretty tight code. <g>


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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Time sink! [Re: Ward Miller POU-NY]
      #419786 - 12/24/15 06:10 PM

Yeah, I know. I remember when a 1GB drive was a big deal. Today, you can't even load a modern OS on one.

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Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Time sink! [Re: Russell Holton]
      #419830 - 12/25/15 06:16 AM

The last is like I saw a LONG time ago, where a physicist wrote that a 386/25 was faster than a Cray.

The 386 took 24 hours to run his problem. The Cray took maybe 100 milliseconds.

BUT....

It took him 26 hours to get those 100 ms on the Cray, so the 386 was done 2 hours earlier than the Cray.

Notice there are no more Crays.

--------------------
Terry
Mostly 0W3


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Terry Carraway
Top Gun


Reged: 06/02/04
Posts: 7098
Loc: Maryland
Re: Time sink! [Re: Russell Holton]
      #419831 - 12/25/15 06:19 AM

Quote:

Yeah, I know. I remember when a 1GB drive was a big deal. Today, you can't even load a modern OS on one.




1GB?


Our first computer had a WHOPPING 105 MEGA byte hard drive. In the days were a 40MB drive was big, and most home computers had a 10MB drive.

First hard drive in a micro computer I ever used was 5MB.

And when I was with HP, the standard hard drive for technical minicomputers was 20 MB, 10MB fixed platter and a 10 MB removable. The removable was about the size of a large pizza box.

120 MB was a multi platter stack about 16-1" in diameter and loaded into a drive the size of a washing machine.

--------------------
Terry
Mostly 0W3


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Ralph Jones
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Reged: 08/31/01
Posts: 21214
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Re: Time sink! [Re: Terry Carraway]
      #419839 - 12/25/15 09:37 AM

Quote:

Notice there are no more Crays.



Well, the supercomputer class isn't dead, but it's largely gone over to "embarrassingly parallel" architecture which is easier to cool...no more $500/gal Fluorinert <g>.

--------------------
Ralph Jones
LS-4a N49LS 6R


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Mase Taylor
Top Gun


Reged: 04/29/04
Posts: 9446
Loc: SOCAL
Re: Time sink! [Re: Terry Carraway]
      #419844 - 12/25/15 11:01 AM

My fist computer had 16k memory and no hard drive. The OS loaded from a 5.25" floppy. My first hard drive was 10mb. I remember how thrilled I was to upgrade to an 80mb drive.

--------------------
Fly The Airplane As Far Into The Crash As Possible. - Bob Hoover 1922-2016 R.I.P.


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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
Time sink! [Re: Mase Taylor]
      #419846 - 12/25/15 11:59 AM

Mase, I bought my first IBM PC in 1981 for $3,000 -- two floppy drives and
16K, display and dot-matrix printer. That's about $7,500 or so in today's
dollars. Today, you can get exponentially more computer for one-tenth that
cost. Quite an improvement in just 35 years.


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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Time sink! [Re: Terry Carraway]
      #419848 - 12/25/15 03:40 PM

Quote:

Notice there are no more Crays.




Too big.

IIRC, the Cray's unique shape was to reduce the distance from the ends so the signal could get from one end to the other quicker.

But modern PCs have a clock speed of around 3GHz. At 3GHz, light (or a clock signal) only travels about 4 inches. Lots of luck clocking anything the size of a Cray that fast. In fact, I think only the CPU in a PC runs that fast. The RAM and other buses run at a slower speed.

Notice that improvements in computing speed seem to come from multi-core. (Dual-core, Quad-core, Octa-core) We seem to have hit a wall on clock speeds. (Although the speed of the various buses have a big effect as well.)

(The clock speed of the original PC was 4.77 MHz. - light travels 200+ feet in a clock pulse.)


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Ralph Jones
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Reged: 08/31/01
Posts: 21214
Loc: 4CO2
Re: Time sink! [Re: Russell Holton]
      #419854 - 12/25/15 04:11 PM

Quote:

(The clock speed of the original PC was 4.77 MHz. - light travels 200+ feet in a clock pulse.)



Back when "Amazing" Grace Hopper was consulting for DEC, she was famous for opening lectures by handing out 30-cm pieces of wire, which she described as nanoseconds...

--------------------
Ralph Jones
LS-4a N49LS 6R


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Ray Tackett
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Reged: 04/30/04
Posts: 8892
Loc: Philadelphia, USA
Time sink! [Re: Ralph Jones]
      #419855 - 12/25/15 05:03 PM

Re 30cm nanoseconds,

Back in that day (1969-70), I worked on Burroughs' Iliac IV. It had four
quadrants of 64 procesors each. Each quadrant was fed work and sent output
to a Burroughs B5500, the second biggest system Burroughs made at the time.
The four B5500s were controlled by a B7700, the biggest there was.

The Iliac processors consisted of circuit cards plugged in to 2X2 foot
backplanes. The pulses were so short that the backplane wiring was done with
very thin 52 ohm coaxial cables. The cable lengths on the backplane had to
be tweaked to get the timing right. For example, the two inputs to a simple
AND gate had to arrive simultaneously or the gate's output could never be
valid. The delay time in the coax also brought up the issue of exactly WHEN
the gate had a valid output, which affected the lengths of other cables.

Then, there was the fun troubleshooting standing waves and ringing when one
or more of the tiny 52 ohm termination resistors went bad or missing.

Lotsa fun tech to that one, all of which became obsolete decades ago.

--------------------
Ray,

Owner, Lake Wood Be Gone

Turning quality lumber into sawdust and noise since 2013.


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Mase Taylor
Top Gun


Reged: 04/29/04
Posts: 9446
Loc: SOCAL
Re: Time sink! [Re: Ray Tackett]
      #419856 - 12/25/15 05:49 PM Attachment (85 downloads)

Quote:


The four B5500s were controlled by a B7700, the biggest there was.









--------------------
Fly The Airplane As Far Into The Crash As Possible. - Bob Hoover 1922-2016 R.I.P.

Edited by Mase Taylor (12/25/15 05:50 PM)


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sreyoB yrraL
AVSIG Member


Reged: 05/16/04
Posts: 9442
Re: Time sink! [Re: Russell Holton]
      #419859 - 12/25/15 08:45 PM

Quote:

(The clock speed of the original PC was 4.77 MHz. - light travels 200+ feet in a clock pulse.)



IIRC, the clock speed on the Z80 CPU in the TRS-80 Model I, my first computer, was 1.78 MHz.


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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
Time sink! [Re: Mase Taylor]
      #419860 - 12/25/15 09:42 PM

Mase, seeing that lady at the tape drive reminds me of an unusual incident
that happened in the early 1960s. I was in a computer room that had about a
dozen 729 tape drives lined up -- this was before disks and was the way we
stored large amounts of data.

All of a sudden, they all stopped and began to unload the tapes from the
vacuum controlled chambers. One of the guys in the room shouted, "Did you
see that?" He then explained a car had just pulled out of the parking lot
in front of the computer room and the reflection of the sun off its
windshield had swept across the line of tape drives.

Back then the tapes had a small piece of aluminum foil near the end of the
tape. It would pass in front of an electric eye and the reflected beam would
signal the drive it was at the end of the tape and shut it down. The
reflected sunlight had swept across all the drives and their electric eyes
"sensed" it was the end of each tape, so each was unloaded.

They had been trying for weeks to find why the tapes would occasionally and
mysteriously unload. Of course they were always looking at the electrical
circuits for the cause.

The next time I was in that computer room, they had curtains on the windows
overlooking the parking lot.


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Ray Tackett
Top Gun


Reged: 04/30/04
Posts: 8892
Loc: Philadelphia, USA
Time sink! [Re: Ward Miller POU-NY]
      #419861 - 12/25/15 10:51 PM

That reminded me of a phenomenon which occurred at a Burroughs plant in
suburban Philadelphia. Every once in a while, all the phones in the building
would ring simultaneously -- just one longish ring.

Eventually, someone noticed that it was associated with trains passing by. The
trains were pulled by GG-1 electric locomotives.

http://pwrr.org/prototype/greenbay/GG1-4890-2.JPG

The ground rod for the phone system was near the rails. Either the soil was
insufficiently conductive or the wire clamp was loose or corroded. A passing
GG-1 would induce about 100 volts AC, which is plenty to ring a phone bell
and there's not a whole lot of current involved.

They got the phone company out to drive a new ground rod well away from the
tracks. End of problem.

--------------------
Ray,

Owner, Lake Wood Be Gone

Turning quality lumber into sawdust and noise since 2013.


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Ward Miller POU-NY
Top Gun


Reged: 05/05/04
Posts: 10508
Loc: New York
Time sink! [Re: Ray Tackett]
      #419871 - 12/26/15 11:19 AM

Ray, speaking of strange phone ringers, a friend was a lineman for Ma Bell
back in the '40s. I woman called to say when her phone was supposed to ring,
her dog barked, but the phone was silent.

Come to find out, she had the dog tied with a metal leash to the phone
company's ground stake. He had been there for several hours and had wet the
ground when he had relieved himself.

When the 48vac ringing circuit tried to sound off, there was not enough umph
to do so because the dog was shorting out some of the path because the
stake was sort of loose. But there was enough to make the dog tremble -- and
bark -- as the lineman found out when he called the lady's number.


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Ralph Jones
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Reged: 08/31/01
Posts: 21214
Loc: 4CO2
Re: Time sink! [Re: Ward Miller POU-NY]
      #419874 - 12/26/15 12:30 PM

Sounds like something in a Terry Pratchett novel...;-)

--------------------
Ralph Jones
LS-4a N49LS 6R


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John O'Shaughnessy [FCM]
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Reged: 09/13/01
Posts: 5059
Loc: Minnesota
Re: Time sink! [Re: Ward Miller POU-NY]
      #419875 - 12/26/15 03:16 PM

Quote:

He then explained a car had just pulled out of the parking lot
in front of the computer room and the reflection of the sun off its
windshield had swept across the line of tape drives.




What a fantastic story!


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Russell Holton
AVSIG Member


Reged: 07/07/05
Posts: 14136
Re: Time sink! [Re: Ward Miller POU-NY]
      #419880 - 12/26/15 03:57 PM

That story reminds me of a article series titled "My Most Memorable Service Call" in a industry field service magazine.

The guy worked for a 3rd party service company and one of the tape drives would periodically fault. Things got worse and IBM was brought in - but they could do no better. So there he was, watching the machine to see when it would fault, when the tape librarian came by to pick up the tapes. When she touched it, it faulted. He had an idea. He went up to the woman and asked if she was wearing silk underwear. "She turned 256 shades of red". That was all he needed to know. He set about isolating the tape drive from the cabinet and the problem was solved.


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