Serial port comunication on PC

Hi, I’m trying to use freeRTOS on an old PC with DOS installed. I am created two tasks:   xTaskCreate( vPLC_Task, "PLC", mainPLC_STACK_SIZE, NULL, tskIDLE_PRIORITY + 10, NULL );   xTaskCreate( vHMI_Task, "HMI", mainHMI_STACK_SIZE, NULL, tskIDLE_PRIORITY, NULL );    Can I use in "PLC" task the functions "_bios_serialcom" of "Watcom C" without necessarily creating a driver for the serial port? Do I need some precaution? Can I have problems? Thanks to all

Serial port comunication on PC

Dont no directly but some openwatcom bios calls leave interrupts enabled so a critical section is not always a possibility.

Serial port comunication on PC

Thanks sotd, Have you any suggestions to create a little slave application that use serial port without write driver? This routine that runs in "PLC" task send data to a master when requested. Thanks Max