[ih] early networking: error checking of main memory

[John Gilmore]

vinton cerf via Internet-history <internet-history at elists.isoc.org> wrote:
> The memory of the IMPs was not error checked in the way current day
> computers do.

At Sun in the 1980s, we put parity checks on all of our memory, and in
later models, offered ECC main memory.  I was horrified when I moved
from Suns to PC's in the '90s and discovered that the vast majority of
IBM PC clones (up to this day) are shipped with no error checking and no
error correction on main memory.  Just like those 1970s IMPs!

Some of this comes from Intel's mendacious attitude that anybody who
wants error checking should pay them more for a CPU chip -- so they
provide none in their cheaper CPUs, which are of course the ones that
are shipped in the highest volumes.

On AMD chips and motherboards, both parity and full ECC have been
supported for generations.  All you have to do to enable it is to use
SIMM or DIMM memories that are a few bits wider (and thus a few dollars
more expensive).  But the Lenovo laptop I'm typing on has no parity nor
ECC on its memory, despite its AMD Ryzen processor.  (The Linux kernel's
boot messages will include something like "EDAC amd64: Node 0: DRAM ECC
enabled" if it's there and working.)

	John