Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!ctrsol!ginosko!uunet!mcvax!unido!rwthinf!franke
From: franke@rwthinf.UUCP (Christian Franke)
Newsgroups: comp.sys.ibm.pc
Subject: Re: HELP! Interrupts on COM ports
Summary: which bit do you mean?
Keywords: COM port, Interrupt, Device Driver
Message-ID: <1235@rwthinf.UUCP>
Date: 26 Jul 89 07:13:51 GMT
References: <1137@rwthinf.UUCP> <1240@crdgw1.crd.ge.com>
Organization: RBI - RWTH Aachen
Lines: 30

In article <1240@crdgw1.crd.ge.com>, news@crdgw1.crd.ge.com (USENET News System) writes:
> 
> This is a common mistake in dealing with the 8250.  The documentation
> is not particularly clear,  so one must read between the lines.  Your
> interrupt service routine must loop on the interrupt pending bit.  So
> long as this bit is clear,  read the IIR and determine the interrupt source.
> When the bit goes high,  send an EOI to the 8259 to clear the interrupt.
> 
> Walt Dixon		{arpa:		dixon@crd.ge.com	}
> 			{us mail:	ge crd			}
> 			{		po box 8		}
> 			{		schenectady,  ny 12345	}
> 			{phone:		518-387-5798		}
> 
> Walt Dixon dixon@crd.ge.com

Which "interrupt pending" bit do you mean? 
Bit 5 of LSR, bit 0 of IIR or a bit in the 8259?


	Christian Franke

	Aachen University of Technology
	Lehrstuhl fuer Informatik I
	Ahornstrasse 55
	D-5100 Aachen
	Federal Republic of Germany
	Tel.: 0241 / 80-3586

	UUCP: franke@rwthinf.uucp ({...mcvax}!unido!rwthinf!franke)