🚀 go-pugleaf

In article <1992Dec30.200952.5153@panther.mot.com> ronf@panther3.panther.mot.com (Ron Feigen) writes:
>Being my first post, I hope this is the appropriate newgroup.
>
>I am a Unix/C/Assembler type that finds himself in the position of having to
>write/port an app. on an IBM PC.  One of the functions needed is to establish
>carrier on a modem.  My problem?  How do I setup the com?: port using 'C'.
>Asking the user to use the DOS mode command would be sort of kludgy.

Well, if you wanted to do what the ms-dos mode command does, it
does an int 21 to set up the serial port. The int 21 is implemented
throught the serial port device driver [also a part of msdos unless 
you've installed a replacement for the default one in io.sys] which
eventually does a BIOS call. The BIOS then talks to the UART directly.

You can of course talk to the UART or the BIOS yourself, and skip msdos
- particularily if you want to program the chip in a method not provided
by msdos/BIOS. The book _DOS Programmer's Reference_ by Terry Dettmann,
published by QUE, covers the MSDOS, BIOS, and UART. [Don't confuse this
book with the microsoft ms-dos programmer's reference - the latter is
only the official programmer's doc for ms-dos 5.]  All C compilers I've
worked with provided library functions for this - check it out.

Someone else has posted how to get the UART spec; you can purchase the
BIOS doc from IBM.

-jen
 Not speaking for microsoft. Just cause I work with msdos doesn't
 mean I'm totally nuts.