These are not dangerous memory resident parasitic viruses, "Pempe.1943" encrypted. They trace INT 13h, 21h, hook INT 8, 21h and on disk access DOS calls search for .EXE files and write themselves to the end of the file. Depending on their counters the viruses decrypt and display the message:
+-----------------------------+
| P E M P E |
| AMACC (Makati,Phils) [PM] |
+-----------------------------+
The "Pempe.1811" virus also contains the text:
PEMPE 1.2
