Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!yale!spolsky-joel
From: spolsky-joel@CS.Yale.EDU (Joel Spolsky)
Newsgroups: comp.sys.ibm.pc
Subject: Interrupts?
Message-ID: <41641@yale-celray.yale.UUCP>
Date: 28 Oct 88 19:31:45 GMT
Article-I.D.: yale-cel.41641
Sender: root@yale.UUCP
Reply-To: spolsky-joel@CS.Yale.EDU (Joel Spolsky)
Organization: Yale University Computer Science Dept, New Haven CT  06520-2158
Lines: 27


If I write an interrupt handler for the COM: port, I know that I have
to outportb(0x20,0x20) to "restore interrupts". Does this mean that
until I do this interrupts are disabled, and I don't have to worry
about my own interrupt interrupting itself?

In other words, in this code:

void interrupt handler(void)
{
  disable();                       <------+ Are these
  /* handle interrupt here */             | statements
  enable();                        <------+ redundant?
  outportb(0x20,0x20);
}

Also, what happens if an interrupt does occur while interrupts are
disabled? will it "reoccur" when interrupts are restored or just
disappear forever?

Reply by eMail please and I'll post.

+----------------+---------------------------------------------------+
|  Joel Spolsky  | bitnet: spolsky@yalecs     uucp: ...!yale!spolsky |
|                | arpa:   spolsky@yale.edu   voicenet: 203-436-1483 |
+----------------+---------------------------------------------------+
                                               #include <disclaimer.h>