Jason Morgan wrote:

> Nice idea, but I don't think errant dram bits hunt and seek just Protel,
> if the dram were faulty, I'd expect 2K (or any component of it) to dump at
> least some of the time, also the bist would be likely to fail...

No, the self test detects functioning memory as different from
empty sockets, but fails to detect all but massively failed DRAM
chips.  It only looks at a few words out of every 1K.

> The majority of PC's though running at GHz frequencies still use either a
> 200 or 266MHz local bus and a 100/133Mhz memory bus, and thats tried and
> tested.

Sure, the memory bus is pretty well characterized, but all memory chips
come off a line where they are tested, and some percentage of them have
bad rows and columns.  The memory testing is not really rigorous, although
most makers retest the 'stick' after placing the cips on it.  I had an old 486
PC that ran Windows 3.1 and other software 'flawlessly', but croaked
fairly often with the old DOS Tango PCB program.  I accused Accel of
faulty software.  I retired that machine years ago, but pulled it off the
scrap heap for some experiments with Linux.  Linux found the hardware
totally unacceptable, although another identical machine ran fine.  It
turns out it had bad memory - I think it was the cache memory, not
the main DRAM memory, but I'm not completely sure on that.
So, at least in that case, it was bad memory that only affected one program,
seemingly.  That WAS, of course, the heaviest program on that system.

> Before I get flamed, I know there are some 400 FSB boards out there with 600
> or even 800MHz memory (no idea how it works though), but we aint got one -
> have you seen the memory prices for it!!!!

They do it by transferring data on both the rising and falling edges of
the clock.  Tricky stuff, with just a couple nS to grab a word of data
as it flies by!


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