DOS--Notes Must install HIMEM.SYS for DOS=UMB or DOS=HIGH You must install the HIMEM.SYS device driver or another extended memory manager before you specify either DOS=UMB or DOS=HIGH. Using the UMB parameter You must specify the DOS=UMB command in order to load programs and device drivers into the upper memory area. Using the upper memory area frees more space in conventional memory for programs. In addition to using this command, you must install an upper-memory-block (UMB) provider. If your computer has an 80386 or 80486 processor, you can use for your UMB provider. If you specify DOS=UMB and no UMB provider is installed, MS-DOS will not display an error message. Using the HIGH parameter If you specify the HIGH parameter, MS-DOS attempts to load part of itself into the HMA. Loading part of MS-DOS into the HMA frees conventional memory for programs. If you specify DOS=HIGH and MS-DOS is unable to use the HMA, the following message will appear: HMA not available Loading DOS low Combining parameters You can include more than one parameter on a single DOS command line, using commas to separate them. For example, the following command lines are valid: dos=umb,low dos=high,umb You can place the DOS command anywhere in your CONFIG.SYS file.