BAT as possible. Read the documentation for the TSR to determine the requirements. There are other A-V products that function very well if installed before there is a virus infection and are used according to their instructions. All the products named are updated regularly , and the current version must be used in all cases. In the worst cases the updates are quarterly.
Most products update every month or every two months, just to keep up.
There are at least 100 new viruses each month, these days. Check every diskette and every download from a BBS or friend, or from the net, and especially from irc and ICQ, before you run it on your computer, with the latest version of two anti-virus products such as those named and you are likely to avoid all but the newest viruses. Instructions for how to do this will be included with all of the better A-V products. Never turn on your computer with a diskette in drive A, unless you are certain that the diskette does not have a boot sector virus. Good luck, and I hope you never need to use these instructions.