By selecting PC DOS 2000 from IBM, you'll get all the features of PC DOS 7 and more. ??It gives you up to 40 KB of additional memory over DOS 6.X. It features RAMBoost, which tracks and monitors how your system uses memory and automatically optimizes it for you, frees up more memory by loading DOS system tables into the upper memory blocks (UMB) area, tracks multiple configuration environments separately, freeing memory. provides more UMB for various cards found in certain 8088 and 286 systems and, depending on the card, gives you an additional 60 KB of memory and lets you load certain device drivers from the command line without having to reboot your system.