Article ID: 39501 - View products that this article applies to.
This article was previously published under Q39501
Below is an example of using the C run-time library function _bios_serialcom() to transmit and receive a single character over the serial-communications port COM1.
The _bios_serialcom() routine simply calls the PC's ROM BIOS interrupt 14h. On most PCs, these routines are not interrupt-driven or buffered. As a result, characters may be lost if a significant amount of processing occurs between status checks and reads and/or when receiving very high-speed transmissions, 1200 baud is the recommended maximum. Although Microsoft does not provide interrupt-driven serial I/O routines with our C compilers, there are several third-parties that do. A partial listing is available in the Language Support Directory that comes with the compiler.
For additional information about ROM BIOS calls, please refer to "IBM ROM BIOS" by Ray Duncan, published by Microsoft Press.
If ROM BIOS routines are not operating as expected, you may need to contact the company that supplied the BIOS for your particular machine.
Article ID: 39501 - Last Review: December 11, 2003 - Revision: 2.0