From: terry AT aegis DOT larc DOT nasa DOT gov
Date: Tue, 28 Sep 93 00:36:09 GMT
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: comm ports

I have a custom serial IO routine with its own device driver that I
have converted into a TSR to use with a GCC (DJGPP v 1.09) program.
I have 'trained' go32 to use the interrupt.  The problem is that when
the TSR (and the device driver, which allows on-the-fly selection and 
setup of the comm ports) is initialized, it appears that the TSR and its
driver really aren't getting hold of the hardware.  The interesting that
is that using a simple test program (one call to the TSR initialization
via an int86) I can get the following results:
1.  a. reboot the machine (device driver in config.sys).
    b. load the TSR.
    c. run the test program (compiled with GCC).
    d. attempt to receive 1 byte.
    e.  --  nothing happens  --
2.  a. reboot the machine (device driver in config.sys).
    b. load the TSR.
    c. run the test program (compiled with Borland C).
    d. attempt to receive 1 byte.
    e. receive 1 byte.
    f. run the test program (compiled with GCC).
    g. attempt to receive 1 byte.
    h. receive 1 byte.
3.  a. reboot the machine (device driver in config.sys).
    b. load the TSR.
    c. run the test program (compiled with GCC).
    d. attempt to receive 1 byte.
    e.  --  nothing happens  --
    f. run the test program (compiled with Borland C).
    g. attempt to receive 1 byte.
    h.  --  nothing happens  --
 
So the question is, does GCC or go32 do anything to the TSR's access to
the comm port?