How do I talk to the comm port under MS-DOS?
If you are programming for MS-DOS, you will need to write an interrupt driven handler for the RS-232 ports. Only the most trival output-only applications can use the BIOS functions built into the PC. Anything that needs reliable input needs to use interrupts. Win16 and Win32 supply drivers that take care of that problem. All you have to learn with those is how to use the API, which is significantly different between the two platforms. For the DOS interrupt handlers you will need to hoist some code into your app. There are sources for PD and freeware code, as well as shareware libraries, with various degrees of utility and quality. I wrote an article a long time ago for Windows/DOS Developer’s Journal called “Servicing Comm Port Interrupts.” It explains every thing you need to do to access serial ports in 16 Bit MS-DOS apps. You can find the whole article on my web page by following the link to “Magazine Articles”, and going way back in the past to May 1990: http://www.dogma.net/markn W
