This has caused the memory used to increase to 7MB, leaving only 80K free. The increase is to support the additional processes running (the X server, window manager, xterm, etc...). Note that the disk buffer didn't shrink, because there is still free memory. Remember: “free” memory means memory that is being wasted.
Now I start up the GNU chess program, having it play against itself. This starts two instances of a rather large program: