MS DOS Command: DOS

Reference from Microsoft MS-DOS cmd help

Description

Specifies that MS-DOS should maintain a link to the upper memory area, load part of itself into the high memory area (HMA), or both. You can use this command only in your CONFIG.SYS file.

Syntax

DOS=HIGH|LOW[,UMB|,NOUMB] DOS=[HIGH,|LOW,]UMB|NOUMB

Parameters

UMB|NOUMB	Specifies whether MS-DOS should manage upper memory blocks (UMBs) created by a UMB provider such as EMM386.EXE. The UMB parameter specifies that MS-DOS should manage UMBs, if they exist. The NOUMB parameter specifies that MS-DOS should not manage UMBs. The default setting is NOUMB.
HIGH|LOW	Specifies whether MS-DOS should attempt to load a part of itself into the HMA (HIGH) or keep all of MS-DOS in conventional memory (LOW). The default setting is LOW.

Related Commands

For information about loading a device driver into the upper memory area, see the DEVICEHIGH command.

For information about loading a program into the upper memory area, see the LOADHIGH command.

Remarks

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 EMM386.EXE 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.