The description below is from the book DOS the
Easy Way by Everett Murdock Ph.D.
for information about downloading the book.
Type: Internal (5.0 and later)
Purpose: Used in the CONFIG.SYS file to specify the memory
location for DOS. It is used to load DOS into the upper memory area
and to specify whether or not the upper memory blocks will be used.
Whenever you use the DOS command in your CONFIG.SYS file, you must
provide at least one option with it. If you want to include more
than one option, you separate them with commas. You must load an
extended memory manager such as HIMEM.SYS in your CONFIG.SYS file
before you can use the DOS=high command option.
For more information about the DOS command, see Chapter 6, Tips for Advanced Users, in the downloadable book DOS the Easy Way.
high|low Tells DOS whether to load itself into high memory (high)
or conventional memory (low). Before DOS can be loaded into high
memory, an extended memory manager (such as HIMEM.SYS) must be loaded.
The default is low.
umb|noumb Tells DOS whether or not it should manage upper
memory blocks (umb) created by an UMB provider such as EMM386.EXE.
The default is noumb (no umb).
To load the extended memory manager, HIMEM.SYS, and then tell DOS to
load itself into high memory and to use upper memory blocks for
memory resident programs, enter the following lines into your