It is not a dangerous memory resident parasitic virus. It hooks INT 21h and when any program is executed, searches for COM and EXE files in the directory from where the program is run, and writes itself to the end of the file. When a debugger is run, the virus displays the text:
On 19th of any month the virus also hooks INT 9 (keyboard) and displays the text " Andreas" at the cursor position.
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Virus.DOS.ADT.1778 or ADT is a memory resident parasitic DOS virus, it is named by the ASCII art...