Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!wuarchive!uunet!dsuvax!ghelmer
From: ghelmer@dsuvax.uucp (Guy Helmer)
Newsgroups: comp.os.minix
Subject: Re: Dumb Questions -- IBM Minix
Message-ID: <1990Dec5.144853.2230@dsuvax.uucp>
Date: 5 Dec 90 14:48:53 GMT
References: <10150@bunny.GTE.COM> <1990Dec4.151849.28931@dsuvax.uucp> <7668@umd5.umd.edu>
Organization: Dakota State University
Lines: 24

In <7668@umd5.umd.edu> cgs@umd5.umd.edu (Chris G. Sylvain) writes:

>In article <1990Dec4.151849.28931@dsuvax.uucp> ghelmer@dsuvax.uucp (Guy Helmer) writes:
>>In <10150@bunny.GTE.COM> seb3@GTE.COM (Steve Belczyk) writes:
>>
>>
>>>   [..] Is there any way to add two more, on COM3 and COM4?
>>
>>Not really. [..] It would be quite a challenge to change the rs232 driver
>>to handle shared interrupt lines, and the additional interrupt service
>>overhead would eat up even more CPU cycles than it does now :-(

>Sorry Guy, but I think it would be much less of a deal than you indicate.
>All the rs232 driver needs to do is read two IIR (interrupt identification
>registers) instead of one.

Yes, that's right.  I goofed, since I never bothered to think about
how to actually handle a shared interrupt configuration.

-- 
Guy Helmer                           helmer@sdnet.bitnet, uunet!dsuvax!ghelmer
work: DSU Computing Services, Business & Education Institute    (605) 256-5315
play: MidIX System Support Services                             (605) 256-2788
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