So yes, this was a TSR, except that it resided in unaccounted for memory. Also, since you put it into the MBR, it would get loaded into ram automatically with e

So yes, this was a TSR, except that it resided in unaccounted for memory. Also, since you put it into the MBR, it would get loaded into ram automatically with every boot, and no fiddling with autoexec.bat or anything where it could be easily discovered. All this of course, in trying to understand the fascinating world of viruses.