Install the file RAMDRV.COM in your CONFIG.SYS file (DEVICE=RAMDRV.COM).
Make sure that RAMDRV.COM is in your root directory and RAMDISK.COM is 
either in your root directory or has a PATH to it.

To create a ramdisk, simply type RAMDISK N, where N is the size (in KB) 
of the desired ramdisk.  To remove the ramdisk, type RAMDISK OFF.  Once 
it's removed, you can create another ramdisk of a different size by
typing RAMDISK N again, where N is some other size.  Batch files (including
AUTOEXEC.BAT) work great for this sort of thing.

The beauty of this ramdisk driver is obvious; you don't need to reboot
to change the size (or delete or create) the ramdisk.