MODEM STATUS

 BBS: Inland Empire Archive
Date: 09-16-92 (23:10)             Number: 253
From: TOM CARROLL                  Refer#: NONE
  To: ALL                           Recvd: NO  
Subj: MODEM STATUS                   Conf: (2) Quik_Bas

I downloaded a public domain door program called Teenage Mutant Ninja
Turtles.  It's written in QB 4.5 for an RBBS system.  What I'm trying to
find out is the how/what/why's & where's of their comm routines.  Here
is one area that I need more info on:

     IF Port = 2 THEN
       MCR = &H2FC
       MSR = &H2FE
     ELSE
       MCR = &H3FC
       MSR = &H3FE
     END IF

     IF INP(MSR) >= 128 THEN  ELSE PRINT "No user online!": END

I understand the INP(MSR) function, and what it's doing, but what I need
to know, is what kinds of status is returned by checking this address.
What is stored there?  Can I check the DTR this way through out the
program to ensure the caller hasn't dropped carrier?  How does this
correlate with the MCR variable?  What is the MCR variable referring to?

Where might I find more info on this, or any comm writing info?

Tom

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