marshg246
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- Jul 12, 2015
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Since resistors have come up again, I was triggered to remember a story.
In the early 80s I worked on Honeywell mainframe computers. One of my customers was beside themselves when their mainframe crashed every day at about 10am. The were especially mad that they had just upgraded their memory and it started the next day. They had gone from 256k words to 512k words of memory (1mb to 2mb). We did that by replacing all their memory boards built with 512 bit chips to 1024 bit chips. Since they were non-military plastic rather than ceramic chips were allowed/used.
One day looking out the window at Dulles airport waiting for and pondering about the crashes, I saw a radiodome airplane take off and down the mainframe went.
Grounded copper screens were emergency installed on the windows and the problem was solved. It could also have been solved by installing memory boards with memory chips made with ceramic casings or in a couple of months by installing boards made with 2048 bit chips. Only the 1024 bit plastic cased chips were affected and then only with certain noise.
The effects of noise on electronics is difficult to predict! Those mainframes cost over a million dollars a year to maintain in the 80s and many millions to buy or lease so they were well tested - testing for everything is simply not possible.
In the early 80s I worked on Honeywell mainframe computers. One of my customers was beside themselves when their mainframe crashed every day at about 10am. The were especially mad that they had just upgraded their memory and it started the next day. They had gone from 256k words to 512k words of memory (1mb to 2mb). We did that by replacing all their memory boards built with 512 bit chips to 1024 bit chips. Since they were non-military plastic rather than ceramic chips were allowed/used.
One day looking out the window at Dulles airport waiting for and pondering about the crashes, I saw a radiodome airplane take off and down the mainframe went.
Grounded copper screens were emergency installed on the windows and the problem was solved. It could also have been solved by installing memory boards with memory chips made with ceramic casings or in a couple of months by installing boards made with 2048 bit chips. Only the 1024 bit plastic cased chips were affected and then only with certain noise.
The effects of noise on electronics is difficult to predict! Those mainframes cost over a million dollars a year to maintain in the 80s and many millions to buy or lease so they were well tested - testing for everything is simply not possible.