The most known viruses of "my time" (even portrayed in local national television) was Cascade, where all the letters fall to the bottom of the screen, and Jerus

The most known viruses of "my time" (even portrayed in local national television) was Cascade, where all the letters fall to the bottom of the screen, and Jerusalem, activating on friday 13th of any month. You were even advised to keep the computer off that day!