Xref: utzoo comp.sys.ibm.pc:38358 comp.lang.pascal:2697
Path: utzoo!utgpu!watmath!att!ima!esegue!johnl
From: johnl@esegue.segue.boston.ma.us (John R. Levine)
Newsgroups: comp.sys.ibm.pc,comp.lang.pascal
Subject: Re: chaining interrupts
Message-ID: <1989Nov16.173228.7309@esegue.segue.boston.ma.us>
Date: 16 Nov 89 17:32:28 GMT
References: <4543@solo5.cs.vu.nl> <1484@geocub.greco-prog.fr>
Reply-To: johnl@esegue.segue.boston.ma.us (John R. Levine)
Organization: Segue Software, Cambridge MA
Lines: 15

In article <1484@geocub.greco-prog.fr> pelegrin@goofi.UUCP (Uncle Ben's) writes:
>     It is absolutely harmless to link interrupt routines one to
>another WITH THE SAME INTERRUPT VECTOR provided that, for interrupts
>such as timer ticks, the total amount of time spent in the routines
>does not exceed the tick clock rate...

Well, sometimes.  The problem is that many cards were not designed with
interrupt sharing in mind and so are not good citizens about the way that
they handle their interrupt line.  I have used cards (a WD8003 Ethernet, for
example) that keep anything else from interrupting on the same level.

-- 
John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 864 9650
johnl@esegue.segue.boston.ma.us, {ima|lotus|spdcc}!esegue!johnl
"Now, we are all jelly doughnuts."