IBM 7074 and then some: "Systems we love" conference

Jon Elson elson at
Mon Jan 23 23:21:35 CST 2017

On 01/23/2017 09:04 PM, Chuck Guzis wrote:
> On 01/23/2017 05:45 PM, Jon Elson wrote:
>> WOW!!!!  That is QUITE amazing!  And, I can't possibly imagine why
>> anyone in their right mind would do this! Seems an emulator on a PC
>> would be faster, and way more reliable, not to mention taking up MUCH
>> less space, power and cooling.  How reliable can a 60 year old
>> machine possibly be? Where do you get parts?  There have to be a
>> whole lot of special parts that are deteriorating, like the plastic
>> parts on the console.  Even the PC boards (IBM SMS cards) are pretty
>> fragile, easily damaged during rework, and some of them dissipate a
>> lot of power, causing slow thermal degradation.
>> Are we SURE this isn't a preview of the April 1st edition?
> I wondered about this too.  Even the USAF eventually replaced the 7080s
> with S/370 running emulation.  Keeping a 7074 running (if my memories of
> keeping a 7094 going are accureate) would be quite some task.
Yes!  There's all sorts of little things that would drive 
you nuts. Things like cooling fans, power supply capacitors, 
cable routing hardware (clamps, ties, etc.)  that they no 
longer make.  it would be a constant job of finding suitable 
replacements for unavailable parts.  The 7000 series had 
"pages" that made up a "book" with tons of old wiring that 
flexed every time you opened up the pages to access the 
circuit cards.  I just CAN'T believe somebody is actually 
keeping such a machine in daily service.  (On the other 
hand, CHM does have a working 1401, that also requires 
folding out racks of boards to access the cards, flexing 
similar cables.)

Wikipedia says the 7070 had 14,000 SMS circuit cards, with 
30,000 transistors and 22,000 diodes.  Having worked on some 
much more recent gear with Germanium transistors, I saw 
about 10% of them were bad.  I didn't run that gear long 
once I fixed it, I sold it on eBay before any more went 
out.  But, I can't imagine that a machine with that many 
components could keep running awfully long between failures.

As for the 1-6 ms response time, that is totally bogus.  The 
article is complete gibberish, talking about a vast library 
of mag tape and ms response time in the same sentence.  
Maybe the 7074 prepares data weekly for some other (newer) 
system that is actually connected online.  And, of course, 
to connect anything to the 7074, you'd have to build custom 
hardware.  RS-232 had not even been invented when the 
7000-series came out.  They did have a 1414 unit that 
apparently was some kind of comm adapter, but I'll bet it 
took milliseconds to send one character.

Oh, and the picture in the article is CLEARLY a posed IBM 
sales brochure photo, and not from the recent operation at 
the unnamed government agency.


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