These files are for PC-Grid file transfer using a null-modem
cable attached to the com ports. The PCMaster.sys must be
entered as a device in your configuration.sys file,
 DEVICE=PCMASTER.SYS or PCMASTER.SYS 2 ( depending on which
com port you have attached the cable) including the full path to 
where the file is. Usually placed in your root directory.
 The PCSlave.com file is placed in your other computer
and the following command is entered:
(directory with path to file)>PCSLAVE or PCSLAVE 2 (depending
on the port you're connecting to.)

The following messages will be displayed:

Slave station ready
Enter commands at master station
Enter Ctrl-C upon completion

 On your master station the drives you are accessing on the slave station
will appear as the next available drives following the assigned drives on your master station. You can then use these drives with any commands with the exception of FORMAT, DISKCOPY, DISKCOMP, FDISK.

 When copying is completed exit the program on the slave station with Ctrl-C.