🚀 go-pugleaf

From: Chris Torek <chris@mimsy.umd.edu>

Alas, testing every one out of every 1K bytes (or other large chunk)
fails miserably as a memory diagnostic.  I suspect that this is
how Imagen's software counts up available memory in the first place;
and I know for a fact that Unix counts up Vax memory using this
method.

Memory diagnostics are subtle things.  There are `walking 1s',
`walking 0s', `refresh delay', `address line short', `data line
short', and other standard tests, yet these do not even begin to
cover some of the interesting faults that can hide in modern dynamic
RAMs.  A good test program will try all of these and will also run
a pseudo-random number generator.  A truly thorough test takes on
the order of eight hours per 64K!

My information on dynamic RAM problems is dated, so my figures
may well be off; but suffice it to say that a power-up self-test
cannot perform a complete check.  Perhaps what Imagen should
provide is parity error detection and/or diagnostic floppies.

Chris