PC99 is a commercial 99/4A emulator.  All the *.dsk files 
in this directory are images of 99/4A disks converted for 
use with this emulator.  *.grm files are command module 
files converted from Gram Kracker module dumps to run on 
PC99.

Information about PC99 is available at 
http://pw2.netcom.com/~mjmw/index.html