[Beowulf] Joe Blaylock's notes on running a MacOS cluster, Nov. 2007

Mark Hahn hahn at mcmaster.ca
Fri Nov 23 14:26:11 PST 2007

> XP?) but used all 1.5 MB naturally with the unix (making it clear to
> me, btw, that the "640K RAM Barrier" was MS's fault, not Intel's).

I'm the last to defend msft, but this 640k thing irks me.

640k is the physical hardware address of the graphics buffer;
IBM put it there.  on the 8086/8088, there is no kind of memory
virtualization, so this is a hard limit on contiguous user memory.
the 286 is very, very different in memory model (16:16 segmentatation - 
you don't want to know more about it unless you like pain)
so this location no longer matters to user-space.  of course, code
assuming only the 8086/8088 model is still 640K-aware.

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