Looking for Real Time Unix

[Bob Lenk]

>                                                               The work
> was done for the Spectrum kernel (HP9000 Model 840, a hot machine), and
> I don't know if it has made it to the 68000 kernel.  The 68000 machines
> (HP9000 Model 320) do have real-time stuff, I just don't know whether
> they have kernel preemption.

I'll try to fill in enough details on the product line to clarify this,
without turning this into an ad.

The real-time work in HP-UX has two sides.  One side is kernel
preemption, as described in the Usenix paper.  The other side is feature
set, including SysV, 4.2BSD, and some of HP's own features (eg.
non-degrading process priorities, file preallocation).  The model 840 is
the only machine with the whole nine yards.  The series 300 and series
200 (68K family, some 10's and some 20's) machines have the full feature
set (or nearly the full feature set, depending on whether a couple of
features are classified as real-time), but no kernel preemption.  The
HP9000 series 500 (proprietary architecture) has most of the features
and a preemptable kernel which has not been as well tuned for real-time
as the 840, and thus does not give as predictable response in all cases.
The Integral Personal computer (68000 based) has most of the features,
but no kernel preemption.

		Bob Lenk
		{ihnp4, hplabs}!hpfcla!rml

Standard disclaimer: The above statements are made my me personally,
and do not represent any official position of my employer.