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Article View: comp.os.msdos.programmer
Article #1134

com port problem

#1134
From: tjb
Date: Sun, 30 Aug 1992 22:55
76 lines
2461 bytes
Hi,
I have an Xt and a 386,
the XT is connected to a printer and a modem
the 386's COM2 is connected to the XT's COM1 through a null-modem
cable.
i want to be able to use the printer&modem from the 386
i can use the printer using a network program, but it's not compatible
with a lot of stuff, and takes up LOTS of memory.
i wanted to use the modem by writing a small C program that
makes the XT transfer COM1 to COM2 and COM2 to COM1
so that COM2(direct link to XT) on the 386 will function as a modem

  386               XT
 ---------      --------------
  COM2  ->   COM1  ->  COM2  ->  modem
    COM2  <-   COM1  <-  COM2  <-  modem


my program so far is:
---------------------------------------------------------
#include <conio.h>
#include <dos.h>

#define COM1 0x3f8
#define COM2 0x2f8
#define COM1S 0x3fd
#define COM2S 0x2fd

main()
{
        int com1,com1s,com2,com2s;

        while( !kbhit() )
        {
                com1s = inportb( COM1S );
                if( com1s & 1)
                {
                        com1 = inportb( COM1 );
                        outportb( COM2, com1 );
                        printf("got %d from com1\n",com1);
                }
                com2s = inportb( COM2S );
                if( com2s & 1 )
                {
                        com2 = inportb( COM2 );
                        outportb( COM1, com2 );
                        printf("got %d from com2\n",com2);
                }
        }
}

-----------------------------------------------------------
i usually get something like
com1:a
com2:a
com1:t
com2:t
com1:<return>
com2:<return>
com2:10
com1:f
com2:f
com1:<return>
com2:<return>

it seems i have some communication with the modem( it only
gives a line feed after commands beggining with 'at') but
i don't get an OK and i can't dial.
i tried calling first and then activating the program. it seemed to have
sent my keystrokes, but pretty limited( missing return, ctrl-break )
and i didn't get any reasonable things FROM the modem.

does anyone know how to make it work??
Thanks,sOmri Barak
Internet: barak@bguee.bgu.ac.il
Bitnet  : barak@bguee
Technical Details
Message-ID: <30AUG92.18554467@enh.nist.gov>
Path: arc1-ca.pugleaf.net!sparky!uunet!dove!enh.nist.gov!tjb

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Path: arc1-ca.pugleaf.net!sparky!uunet!dove!enh.nist.gov!tjb
From: tjb@enh.nist.gov
Newsgroups: comp.os.msdos.programmer
Subject: com port problem
Message-ID: <30AUG92.18554467@enh.nist.gov>
Date: 30 Aug 92 22:55:44 GMT
Sender: news@dove.nist.gov
Organization: NIST
Lines: 78