Let us see some of the thing that you should follow to keep the virus away from infecting your system.
To prevent a virus infection one method could be to never to use the floppy disk network, modem etc., but this is not possible in the real life, without and exchange of data and program a computer will not be much use.
Therefore, to prevent a virus infection one can take some precautions such as
Keep the floppy disk drive door open
whenever the system is booted from a hard disk drive, if you have some disk in the floppy drive then keep the drives door open.
Keeping the door closed will give the boot sector virus from the floppy disk to become active. Once again use a boot sector infected floppy disk to read and write data, but only when the system is booted using the infected floppy, even if it is not a bootable floppy, the virus will get a chance to become active.
Do not use pirated software
Pirated software, specially games and demonstration packages are one of the main carriers of the viruses.
Buy original software from the known dealers, this will keep your system virus free.
Get share ware for some reputed company/BBS
Shareware software should be obtained from some reputed dealer, well known BBS operator or directly from the program author. This again will reduce the chance of virus infecting your system.
Run virus scanner/checker program regularly
One should run the latest available virus scanner program regularly. DOS provides MSAV (Microsoft Anti Virus) program with the current verson of DOS. this can be used to regularly check the system for any infection.
Also some other food virus scanning programs such as Nashot from Nash Systems, IAVT, SCAN from McAfee Associates, Norton Anti Virus from Norton etc available.
Use a memory resident anti virus program
Use some memory resident, TSR (terminate and stay resident) program, that can monitor different activities on the system and inform the user of any program tries a virus like activity such as directly writing to the FAT table, writing on track 0, formatting hard disk, trying to be memory resident etc.
Current verson of DOS provides a TSR program for this purpose known as VSAFE. This program can be made memory resident and made to alert the user on different virus like activities.
Use write protect tab on the floppy disks
Always the floppy disk containing program must have read only tabs on them. Also, if you are taking your data files on floppy to some other place for reading then put the read-only tabs on them because even if there is no executable program in them the boot sector of the floppy could become infected.
Always keep current verson of Anti-virus software
Everyday some new virus is made so, you cannot get a virus scanner, install it and forget about it. The old virus scanner may not recognize new viruses so always try to get the latest verson of lthe scanner software. keep the software uptodate by getting current verson.
Backup the data regularly
Finally, even after all this precaution you may get infected. Therefore, whatever protection you follow, you must backup your important data regularly. This will help in the worst virus infection. You can always reformat and restore the data.
Watch out when you get a service Engineer's visit
One main source of virus infection on many computers is the computer service Engineers. These SE's carry diagnostic diskettes with them and use it on many different systems. Most of the time these disks are not write protected. Even if these disks are write protected, sometime when they see some good utility on a system they copy it on their diskette. This gives the virus in the system a chance to infect these disks.
Do not open e-mail attachments from unknown address
In this Internet era, the e-mail attachment are one of the biggest medium of virus infection. One should never open an e-mail attachment coming from unknown address. Even attachments from known addresses should be scanned with latest anti-virus software before opening.
Take care when downloading files from Internet
When downloading files from the Internet is should be scanned properly. Download files from reputable web sites such as shareware.com, download.com, tucows.com etc.