Summary

Most boot sector viruses hide by lowering the amount of RAM visible to the operating system and hiding in the free space they create. EDV is different. It searches for free RAM, starting at E800 and searching downwards. It is also unusual on one other way - on every timer tick it will check if ES or DS point to it - which is possibly the case if a virus-scanning program is running. In this case a HLT instruction is executed - which halts the computer.

Additional Details

Aside from this, the virus is fairly usual. It marks infected diskettes with a "EV" at the end of the boot sector and stores the original boot sector code in the last sector of the last track on 360K diskettes, just like the Yale virus.

One encrypted text string is stored inside the virus code:

                    That rings a bell,no ? from Cursy