Cathode ray tubes were also used as RAM in early computers:
https://en.wikipedia.org/wiki/Williams_tube
One of these computers was the machine at Manchester that Alan Turing worked on:
https://en.wikipedia.org/wiki/Williams_tube
One of these computers was the machine at Manchester that Alan Turing worked on:
There were two sources of noise: external noise, from stray electromagnetic fields; and internal noise, caused by leakage of electrons when reading from or writing to adjacent spots. External noise could, for the most part, be shielded against, and internal noise was controlled by monitoring the "read-around ratio" of individual tubes and trying to avoid running codes that revisited adjacent memory locations too frequently -- an unwelcome complication to programmers at the time. The Williams tubes were a lot like Julian Bigelow's old Austin. "They worked, but they were the devil to keep working" Bigelow said.
This phenomenon is very similar to the recently discovered row hammer vulnerability of DRAM memory, except it predates it by roughly 65 years.
The biography Alan Turing: The Enigma (which I highly recommend) also goes into a lot of detail about the early computers that Turing worked on:
https://www.amazon.com/dp/069116472X
I learned about Turing Machines as a CS student a long time ago, and got the false impression that he was only involved in theoretical pursuits (theory of computation, algorithms for cryptography, etc.). It was only after reading this book that I learned how much he had contributed to the design of actual computing hardware.
> trying to avoid running codes that revisited adjacent memory locations too frequently
And today, it's exactly the opposite: we try to write code that has as much locality of reference as possible so that we can avoid expensive cache misses.
* A CRT RAM thing. It's a refreshing RAM that takes advantage of the persistence of the the phosphor glow.
From: