Intel's Ministry of Truth has almost, but not not completely
eliminated references to this part from their website, so I can't find
a datasheet.  Anyone got a copy of this stashed somewhere?

The Intel multiprocessing interrupt architecture involves multiple
APIC units -- one for each CPU, and one or more for I/O interrupts;
they talk over a 3-wire bus tossing interrupts back and forth at each
other.

The i82489DX is the "old" Local APIC (Advanced Programmable Interrupt
Controller), which was used in early pentium MP systems; late-model
Pentiums and all P6-class CPU's have a Local APIC on-chip.

I've got the doc for the I/O APIC, and the on-chip local apic is
documented in the intel system programming book, but the latter only
glosses over the programming differences between the onboard APIC and
the i82489 -- so, for completeness, I'd like to get a copy of the
original datasheet if I can.

Also, any additional information on "focus processor" mode would be
useful; the spec I have is somewhat vague about what it means.

					- Bill