Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!amdcad!diablo!phil
From: phil@diablo.amd.com (Phil Ngai)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Interupt conflicts
Message-ID: <26905@amdcad.AMD.COM>
Date: 23 Aug 89 01:12:33 GMT
References: <[1580.2]comp.ibmpc;1@point.UUCP> <176@tabbs.UUCP>
Sender: news@amdcad.AMD.COM
Reply-To: phil@diablo.AMD.COM (Phil Ngai)
Organization: Advanced Micro Devices, Inc. Sunnyvale CA
Lines: 28

In article <176@tabbs.UUCP> martin@tabbs.UUCP (Martin Walker) writes:
|The standard design philosophy used in designing interrupt control circuitry
|is to make all the interrupt line drivers open-collector. This means that

Not in PCs it isn't.

|On most PC's, however, each peripheral has 
|its own interrupt line, obviating the need for software polling, 
|but the drivers ARE usually still open-collector

No, you're wrong.

|I cannot say for sure if this sensible design philosophy was 
|followed in the PC in question, but I would be rather 
|surprised if open-collector logic hadn't been used. It is 
|after all less complex than fully driven logic....

If you're so unsure of yourself, how can you make the strong
statements I just quoted?  In fact, you and many others posting on
this subject don't know what you're talking about. Do you just like to
hear yourself talk, whether or not you're right? 

For your information, not that you seem to care, interrupts on the PC
bus are active HIGH. 

--
Phil Ngai, phil@diablo.amd.com		{uunet,decwrl,ucbvax}!amdcad!phil
"Nonviolence works! India hasn't had to use their nuclear weapons yet."