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Sherlock Ohms

The Adventure of the Suicidal IC's

October 7, 2009

With ICs jumping off boards and more ready to make a break for it, an engineer helps out a competitor

By Bob Cowell, Contributing Writer

Around 1982, the new hotshot Silicon Valley company was Silicon Graphics (SGI), rumored to have a killer computer graphics demo. I was still at Carnegie-Mellon University as a grad student, but was working part-time at Three Rivers Computer, an engineering workstation startup that was paying me to develop a color graphics version of their original black-and-white workstation.

I had gotten involved with Three Rivers (later renamed to Perq Systems) for two reasons: 1) I had seen a really fascinating demo by them with graphical windows sliding around on the screen, under and over each other, and I simply had to know how they were doing that (turns out they were faking it, at least originally); and 2) I wanted to design things as a break from grad school research. Because I was designing a color graphics engine, I was eager to see how my design would stack up against the new kid on the block.

I arrived early at the classroom where the SGI demo was to be held, only to find the SGI presenter muttering to himself with his head stuck in the back of the chassis. It quickly became clear that his demo machine was not working. Argh. I really wanted to see that demo.

Several minutes later it was becoming clear that this demo was not going to happen. So I figured I might as well see what was in the chassis; at least this presentation wouldn’t be a complete waste of time. I asked the presenter if he minded if I looked around, and with an exasperated sigh he said sure.

The first thing I noticed were the usual array of printed circuit cards stacked on their sides, plugged into a backplane. Nothing unusual there; looked like lots of TTL. But what DID seem unusual was that there were approximately ten IC’s lying on their backs on the bottom of the chassis.

Now, that was a problem I knew something about - the old DIP IC’s often had a tendency to “walk” out of their sockets due to the vibration of the cooling fans or during transportation. Some socket types were far worse than others for this problem. I sometimes resorted to using little nylon cable clamp “seat-belts” to keep the IC’s from going on walkabout.

I asked the presenter if he’d mind if I tried to find out where these IC’s had fallen out. He probably figured I couldn’t really do any harm, and waved a hand in my direction that I took to mean “okay.” It’s not as hard to find the proper homes for these IC’s as you might think, because many of them are “sliced”; a ‘244′ octal buffer is likely to be found in the company of other ‘244’s to carry a 32-bit bus, for instance.

In about ten minutes I had found likely homes for all of the escaped IC’s, re-socketed some other chips that were “making a break for it,” and suggested to the presenter that he try the machine again. I held my breath - it worked. And the darned demo was great, to the point where I had to mentally revise the expected market for what I was designing. I really enjoyed seeing SGI’s demo, but I always wondered if directly helping a competitor was a legitimate part of my job description.

Contributing Writer Bob Colwell was Intel’s chief x86 architect in the 1990s and has worked as a computer designer at VLIW pioneer Multiflow, Perq Systems, and Bell Labs. Author of The Pentium Chronicles and the At Random column in Computer Magazine 2002-2005. He is currently an independent consultant.

Posted by Sherlock Ohms on October 7, 2009 | Comments (17)

November 17, 2009

In response to: The Adventure of the Suicidal IC's
deaf computerman commented:

Have had the same problems for years in both Apple IIe and IBM computers. Reseat the chips and everything works again.

November 15, 2009

In response to: The Adventure of the Suicidal IC's
masimons commented:

Made some trips from IL to Amsterdam and Singapore back in early 80's due to similar problems, but no out of socket IC's, just had to reseat. Made for great little vacations.

November 14, 2009

In response to: The Adventure of the Suicidal IC's
skenn_ie commented:

If it's a short production run, use turned-pin gold plated ... if it's volume, solder every time !.

November 13, 2009

In response to: The Adventure of the Suicidal IC's
getter commented:

Loctal plugs and sockets helped keep vacuum tubes properly seated in mobile and aviation radios and equipment...The "walk-out" component problem has been around for a while.

November 3, 2009

In response to: The Adventure of the Suicidal IC's
twodogs commented:

I had a EE prof in the early 80s, very prescient, who claimed one day "It's always the connectors! I don't care how advanced the technology, when there's a problem, it's always the connectors!"

November 2, 2009

In response to: The Adventure of the Suicidal IC's
Old tech commented:

We had a main board that mounted on the back of a front panel keyboard in our fuel terminals. People would get denied fuel and punch the terminal, sending the chips flying inside the machine. It was routine for us to reseat all of the RAM and 2764 program chips (in sockets). They would reseat with a loud SNAP!! We eventually had to start using machined sockets instead of the spring ones and zip tie them down.

October 28, 2009

In response to: The Adventure of the Suicidal IC's
Headhunter commented:

In the Navy during the late 80's I watched the tech massage the the circuit boards on a Honeywell simulator system after an unexplained (and frequent) system failure.
The system I was trained for (that they simulated) didn't seem to have that problem. After watching them toggle in several Kbytes of data, I was glad I was the instructor and not the tech.

October 24, 2009

In response to: The Adventure of the Suicidal IC's
dscc1947 commented:

I know this problem. I worked on a DEC PDP-8
clone and almost all the ttl logic had a metal
clip around each of the logic ic's.

October 23, 2009

In response to: The Adventure of the Suicidal IC's
BillSiliconValley commented:

I saw ICs fall out or partially work out of cheap sockets dozens of times. Re-seating loose ICs was a standard procedure. Much of the better quality equipment, like mainframes and test gear, did not have this problem. There was a real price premium and considerable pressure on designers to use the cheap sockets.

October 22, 2009

In response to: The Adventure of the Suicidal IC's
LeeM commented:

The cheap single flat contact IC sockets were well known for this. The wrap sockets typically had 4 contacts in machined cylinder and were significantly better.
I also once saw a "passing" shipping test report for a rack mount PC where the company claimed no damage since the system would work once the boards were re-seated..

October 22, 2009

In response to: The Adventure of the Suicidal IC's
K1200LT rider commented:

In all the years as a technician during the 80's and 90's, I never saw an IC physically come out of a socket on its own. I was an arcade video game and pinball technician, and a lot of the machines' logic boards had sockets. I was also a mainframe computer tech for 8 years, and some of that old stuff was loaded with wire-wrap sockets. Maybe all the stuff I worked on never had to endure an extreme amount of vibration. However, I have seen many problems fixed simply by reseating ICs and connectors (especially ribbon cables).

October 22, 2009

In response to: The Adventure of the Suicidal IC's
William Ketel commented:

It really is amazing the problems that come from skimping on IC sockets. I once repaired a tester machine in an auto plant by re-seating the ICs on a display driver PCB. The tester operator watched me do this and started laughing. I asked him what was that funny, since he was really enjoying it. He explained that I had just fixed the machine in 3 minutes, while one of the aoto plant electricians had struggled with the machine for two and a half days, before they called for an outsider to fix it. I had a good laugh with him at that point.

October 22, 2009

In response to: The Adventure of the Suicidal IC's
Real life commented:

These sockets made a factory looked like they had thrown the chips in the PC. And making the recipient not believed they were actually tested before shipping.

October 21, 2009

In response to: The Adventure of the Suicidal IC's
Brad Wood commented:

That's a wonderful story. It reminds me of the scene near the end of Real Genius, when Professor Hathaway notices an EPROM on the floor of the aircraft near the navigational controller (left there as Chris and Mitch have departed hastily, barely eluding discovery), and tries to find a socket that it fits in.

October 19, 2009

In response to: The Adventure of the Suicidal IC's
bob colwell commented:

Wean Hall always seemed in need of space heaters (or outright demolition) to me...but it's good if the space heaters actually do computation as a side-benefit!

October 15, 2009

In response to: The Adventure of the Suicidal IC's
Charly commented:

Well, with very cheap sockets this was likely to happen after transport. I've seen another kind of suicide IC with the early use of SMDs in a CAMAC crate (kind of 19" rack for instrumentation). The fan was stuck, and a '244 was unsoldered by the heat on the dense populated PCB.

October 13, 2009

In response to: The Adventure of the Suicidal IC's
ewertz commented:

Ah, the Perq... a dream machine (to me, anyways) at the time. And a fantastic space heater, perfect for the chilly cinder-block offices in Science (not Wean) Hall.

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