Xref: utzoo alt.msdos.programmer:21 comp.sys.ibm.pc:28565
Path: utzoo!attcan!utgpu!tj
From: tj@gpu.utcs.utoronto.ca (Terry Jones)
Newsgroups: alt.msdos.programmer,comp.sys.ibm.pc
Subject: Re: Switching COM: Ports
Message-ID: <1989May10.111641.8831@gpu.utcs.utoronto.ca>
Date: 10 May 89 15:16:41 GMT
References: <412@carroll1.UUCP> <542@megatek.UUCP>
Reply-To: tj@gpu.utcs.UUCP (Terry Jones)
Organization: University of Toronto Computing Services
Lines: 10
Checksum: 05136

Even programs that go directly to hardware may work with the "switched"
com ports. There is an area in memory that stores the hardware addresses
of installed ports (40:0) and software that actually looks there to find the
address of com1 or 2 should switch properly. In this guy's case maybe he
will get lucky in that ONE and ONLY ONE of the programs he wants to use
with com1 will look at the address to find where the hardware is and go there
and if they are switched then it will access com2, now if the other program just
goes to hardware at com1 address then they will behave!

tj