$SOURCEDRIVE$ is assigned the value of the drive on which the installation occurs and is usually the floppy disk drive which has your installation disk in it. This variable is similar to $SOURCEDIR$. However, it contains the drive value (one letter) only and not the directory value.

For example, using a variable to define a device driver for a CD-ROM drive in a .ini file using the INIFILE command or Config.sys file using the CONFIG command.