Re: Interrupts

[Nathaniel Mishkin <Mishkin@YALE.ARPA>]

    Is there provision for user programmable interrupts in T? In
    particular, we want to run a slave CPU asynchronously from the
    RS-232 port of an Apollo.

The Apollo system interface is not "interrupt-oriented".  I.e. instead
of having "software interrupts" (ala Unix and TOPS-20), it has "events".
System resources (e.g. input pads, SIO lines) have "event counters"
associated with them.  The way you "simulate" interrupts is by waiting
on a set of event counters.  So if you want to be able to read from
the keyboard (i.e. input pad) while waiting for an SIO event, you wait
on the event counters for the input pad and the SIO line.  When you
unblock, the system call returns what event happened.  You then process
the event (e.g. read from the SIO line) and block again.

This is all do-able from T.

Stop by and see me if you want more information.

                -- Nat
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