On Wed, 19 Feb 2003 17:33:38 +0100, Phil Payne <[EMAIL PROTECTED]> wrote:
>> ECC wasn't pervasive in mainframes also. I remember hearing of a >problem with a 3081 which turned out to be cosmic rays (really) which >occaisionally changed bits in a channel buffer cache... which had >neither parity nor ECC. > >The first machine I know of that detected single bit errors throughout the system was >the >Hitachi S7 - roughly equivalent to the 3083. > >You can get single bit errors with no external influence at all - just from quantum >mechanics. And Lord protect you if the packaging accidently contained materials which generated gamma rays. Another tale of woe from the IBM 1980s which shutdown foundry production for several months.. >You never know where an electron realy is - it's a probability thing. There is a >chance that >all of the electrons constituting a charge will jump to the left at once - creating a >false >zero or one at the output to the gate. > >I remember a discussion with a CPU designer. > >"How often does this happen?" > >"Every million years or so with these transistors, more often with the smaller ones >we plan in >the future." > >"Uh huh. So why is it a problem?" > >"Nineteen transistors per bit, eight bits per byte, 64MB. One single bit every >couple of >hours." > >That was about 1985. > >I liked the microcode store recovery system. There were two banks with identical >contents, >interleaved for speed. If a single bit error occured, the machine just waited for >the next >half-cycle and took the value from the other bank.
