INF: Accessing the COM3: or COM4: Port

ID Number: Q40594

5.x 6.00 6.00a 6.00ax 7.00

MS-DOS

Summary:

If MS-DOS, the ROM BIOS, and the hardware all support COM3: and COM4:

as valid devices, then the MS-DOS MODE command may be used to redirect

communication to access the ports from within Microsoft C. For

example, to redirect COM3: to COM1:, give the following command:

mode COM3:=COM1:

Note: This process has not been tested by Microsoft and is offered

only as a suggestion.

Versions of MS-DOS earlier than MS-DOS version 3.3 do not recognize

the COM3: and COM4: ports. Versions beginning with MS-DOS version 3.3

allow some systems to access the ports, but the ROM BIOS also must

support the extra communications port hardware.

Additional reference words: 5.00 5.10 6.00 6.00a 6.00ax 7.00