Path: utzoo!attcan!uunet!peregrine!ccicpg!turnkey!conexch!rob
From: rob@conexch.UUCP (Robert Collins)
Newsgroups: comp.sys.intel
Subject: Re: Interrupt/Exception Confusion on PC/AT
Keywords: 80286, PC/AT, Interrupts, Protected Mode
Message-ID: <11368@conexch.UUCP>
Date: 4 Nov 88 08:49:25 GMT
References: <385@ives.randvax.UUCP>
Reply-To: rob@conexch.UUCP (Robert Collins)
Organization: The Consultants' Exchange, Orange County, CA.  (714) 842-6348
Lines: 27

In article <385@ives.randvax.UUCP> edhall@randvax.UUCP (Ed Hall) writes:
+I may be missing something obvious, here:
+
+When running an 80286 in protected mode (and for some limited cases
+in real mode) it is possible to generate exceptions with vector numbers
+between 0x8 and 0xf.  Now, on a PC/AT, COM1 is at INT 0xa--which is
+the INT for a stack overflow.  Just how do you tell the two apart?
+How about LPT2 and a general protection violation?  In fact, all of
+these vectors have some flavor of PC/AT hardware that claims them.
+
+Of course, the INTEL 80286 reference says all over it that INT 0x0 to
+INT 0x1f are ``reserved by INTEL.''   Maybe the folks at IBM can't
+read...
+
From what I understand, when the 286 came out, (and actually was capable
of generating these interrupts,) IBM tried to bully intel to changing
a few things.  Intel said:  "We told you not to use them in the first
place."  Intel subsequently wouldn't back down...which really screwed
IBM (and all other clones...since we all must be compatible).

If this isn't true, then it certainly sounds good!

-- 
"Worship the Lord your God, and serve him only."  Mat. 4:10
Robert Collins                 UUCP:  ucbvax!ucivax!icnvax!conexch!rob
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