Once you have the size of the RAM disk specified, you then specify what you want to put in it. Here, the manual is effective, if somewhat outdated. Anything you want to put on the RAM disk, you can. You need to specify what you want, and prioritize the items. Maxima will then come back and inform you if you need to modify the size of the RAM disk.
Controls are easy to use.
The real use of a RAM disk is in what you store on it, and here is where I feel that the manual is dated. My computer use really doesn't include most of these items. I have found Maxima especially useful for two items, Netscape caches and disk inventories. Even taking into account the varying connect speeds with my ISP, I find that relocating the caches from my start-up drive to Maxima decreases the speed of reloads of sites significantly. The second major use is for my disk archiving.