Jim Lawless is a programmer specializing in C development for
Windows for a financial institution. He teaches C & Visual BASIC
programming at a local college. He can be reached at
email@example.com or 2414 4th Ave., Council Bluffs, IA 51501.
The number of people who utilize online services and electronic
bulletin-board systems grows each year. Despite public interest
in telecommunication, accessing a modem from an MS-DOS
application has been a somewhat arcane science. MS-DOS provides
extremely minimal support for access to the RS-232 communication
ports. In fact, MS-DOS relies heavily on the hardware Basic
Input/Output Subsystem (BIOS) to handle all of the dirty work
related to utilization of a modem as an I/O device. The major
problem with utilization of BIOS communication routines is that
characters that are sent and received are not buffered. An
application must poll the ports frequently to avoid losing data.
Although the BIOS does not readily support lossless RS-232 I/O,
the Universal Asynchronous Receive