You may create a swap file on disk to augment RAM, using Watcom's ``Virtual Memory Manager'' (VMM), and use more memory than your machine actually has. When RAM is not sufficient, part of the program is swapped to the disc file until needed. The combination of the swap file and available RAM is the virtual memory.
To specify virtual memory, set the DOS environment variable, ``dos4gvm'' by entering the following at the DOS prompt:
``set dos4gvm= [option[#value]] [option[#value]] ...``
or ``set dos4gvm=1'' to accept all defaults.
the VMM options and default values are listed below,
minmem The minimum amount of RAM managed by VMM, default 512KB
maxmem The maximum amount of RAM managed by VMM, default 4MB
swapname The swap file name, default ``dos4gvm.swp`` in the root directory.
virtualsize The size of the virtual memory space, default 16MB.
For example ``set dos4gvm=maxmem#8192 virtualsize#32768
swapname#c: 
ddlab ddlab.swp'' gives 32MB of virtual memory
and a swap file called ``ddlab.swp'' in the ``ddlab``
directory. Note that the virtual memory available will be displayed
in the memory window in DDLab, as described in #4.3.1 above.