Path: utzoo!attcan!uunet!husc6!m2c!necntc!encore!paradis
From: paradis@encore.UUCP (Jim Paradis)
Newsgroups: comp.os.minix
Subject: Re: posting of tty.c
Keywords: shar fix tty.c
Message-ID: <3285@encore.UUCP>
Date: 5 Jul 88 13:49:50 GMT
References: <2827@ttidca.TTI.COM> <833@ast.cs.vu.nl>
Reply-To: paradis@encore.UUCP (Jim Paradis)
Organization: The Whizzo Chocolate Company
Lines: 21

In article <833@ast.cs.vu.nl> ast@cs.vu.nl (Andy Tanenbaum) writes:
>One question, perhaps somebody can help me.  I sort of have the feeling that
>RS232 port 1 uses vector 12 and port 2 uses vector 11.  Is this correct?

Absolutely correct.  Actually, ports 1 and 3 use vector 12, and ports 2 and
4 use vector 11.  If you have more than one port per vector, you then have
to go and read status registers to figure out exactly who interrupted.

>I have scoured the IBM XT Reference Manual from cover to cover, and--silence.

Not quite silence.  There is a small table of interrupt NUMBERS buried
somewhere in the book... you then have to go to the BIOS source code
listing to get an idea of how interrupt numbers map to interrupt vectors,
and take it from there.

>Andy Tanenbaum (ast@cs.vu.nl)


-- 
Jim Paradis, Encore Computer
(.signature undergoing renovations. Please pardon our appearance.)