On  2 May 98 at 13:42, John Hornbuckle wrote:

> >Can someone please explain the difference between parity and non-parity
> >RAM? I presume I cannot mix and match the two? If I can't mix, how do I
> >tell which version (parity or non-parity) that I already have installed?
> >Obviously, I want to install these 2 new SIMMS myself, but do not want to
> >be caught with useless parts due to my ignorance.
>
>    I may be wrong, but I believe that all EDO RAM is non-parity. I also
> believe that parity RAM isn't used much any more (in newer systems, I mean).

  "ECC" RAM is RAM with parity bits.  The thing is that once you get
up to 64 data bits wide (Pentium, 2 72-pin SIMMs or one DIMM), you
can have enough "parity" bits to implement ECC, which allows
on-the-fly correction of errors that simple parity would only catch,
and catching of errors that simple parity would miss.  This is an
attractive choice, especially for servers where a small investment in
reliability is easily justified.
  Both EDO and SDRAM are available in ECC varieties, and some
motherboards allow configuration to do simple parity checking instead
of ECC.  [The only time you'd want this is when the motherboard's
implementation of ECC is known to be defective.]

David G