Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!mailrus!tut.cis.ohio-state.edu!fortin
From: fortin@tut.cis.ohio-state.edu (Micheal Fortin)
Newsgroups: comp.os.xinu
Subject: Re:  putting a char to console (SUN Xinu)
Message-ID: <13973@tut.cis.ohio-state.edu>
Date: 23 May 88 17:58:03 GMT
References: <8805231449.AA09097@merlin.cs.purdue.edu>
Organization: The Ohio State University Dept of Computer and Information Science
Lines: 24

In article <8805231449.AA09097@merlin.cs.purdue.edu> comer@PURDUE.EDU (Douglas Comer) writes:
>
>   As for bypassing the the device switch table, I think you
>overlooked something.  Even in the early versions of Xinu, the
>iint and oint entries in the device switch table were consulted
>at system startup and then stored in the intmap table that
>gets used by the interrupt dispatcher.  The reason is simple --
>it's too inefficient to index the device switch table on every
>interrupt.
>
>Doug

Yes, it is a good idea to consult the device switch table only at
start up and then storing the info in the intmap table. But the
Sun 3 implementation of Xinu7 has somehow gotten by without the
use of the intmap table. ( Probably because each device has its own
interrupt mechanism, instead of having one interrupt mechanism for all
I/O like the book has) Even if there was an intmap table in use,
it still could not have consulted the device switch table for the 
necessary interrupt dispatcher information, because the device switch
table doesnt contain the correct entries.

Anyway, thanks for the information concerning these matters.

mike