Dave replies:
> 1) How does one (or where does one find info to) mark a program
> as resident?

If you have to ask then you don't need to do it :-)

> 2) Is it correct that MPE or HP3000s do not make good real-time machines
> because all serial connections are polled rather than hardware interrupt
> driven?

Serial connections are not polled.

> Perhaps the designers had imagined some specialty I/O cards that
> would handle hardware interrupts?  IIRC someone once told me that neither
> the OS nor the hardware were set up to handle hardware interrupts (except
> maybe internal hardware, possibly the IEEE488, er... I mean HPIB).

Completely untrue.  Both Classic and PA-RISC 3000s are fully interrupt
driven.

Having a real-time OS basically means being able to guarantee worst-case
latencies on interrupt handling.  The problem in doing this is not that it's
hard to create a process which will have a high enough priority, but that
you have to guarantee that other interrupt-driven processes will never keep
interrupts disabled longer than your worst-case latency requirement.

For small values of "real" and large values of "time" MPE can be made to
look like a reasonably real-time OS in some cases.  The question is not how
to make MPE real-time, it's what do you want to accomplish, and what's the
best way of doing so.

G.