>Just like to get a confirm answer from expert whether Microsoft DOS 6.22 is Y2K compliant ?
>
>Because our POS software is running on top of it, and testing confirm it okay with Y2K hardware. However, I am confused then, why IBM come out with a PC DOS 7.xx that is Y2K compliant

You can check any of MicroSoft's products at http://www.microsoft.com/year2000
For information on DOS see http://www.microsoft.com/technet/year2k/product/user_list.asp

Dos is officically "compiant with minor issues"