"Do the address of com1 and com2 2f8 and 3f8??"

The other way round:
COM1: 0x3f8
COM2: 0x2f8
COM3: 0x3e8
COM4: 0x2e8

As noted by other posters in this thread, DOS software generally works fine in a DOS box under XP. Port IO using in, inp, inport, inportb etc (or whatever your compiler calls these things) is fully supported. Problems that arise tend to be due to assumptions made about timing, or just straightforward bugs (usually wild pointers) that may have gone unnoticed in a traditional DOS environment. It would be a tall order indeed to expect the virtual machine to replicate undefined behaviour correctly, largely due to there being no definition available for 'correctly' in this situation.