> [...]
> ECC is just parity RAM, the memory controller in the chipset detects
> single bit errors and recalculates the correct bit.
That would be a good trick. A parity bit will let you find out about a
single-bit error, but you need more redundant bits to tell you which bit
to invert. If your memory is organized as 32-bit words, for example,
the controller needs to come up with a number between 0 and 31 to
identify the bad bit. That takes another five bits.
>
> In my experience, parity (ECC) memory does seem to cure some strange
~~~~~~ ~~~~~
Please! These are not the same. Parity (unless the marketing types have
been eating holes in the dictionary) is counting whether the number of
stored "1" bits is odd or even. ECC is Error Checking and Correcting,
and implies at least the capability to detect and correct all single bit
errors AND to detect all double-bit errors AND to detect an all-zeros or
all-ones (counting the redundant bits, of course) condition.
--
ted@psg.com ted@wimsey.com http://psg.com/~ted/ (Ted Powell)
"Circular logic will only make you dizzy, Doctor!"
--Perpugilliam Brown