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DOS


Description | Syntax | Parameters | Switches | Related | Notes | Examples | Errorlevels | Availability

Specifies that the operating system 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[,[NO]UMB]

DOS=[NO]UMB[,HIGH|LOW]


Parameters
HIGH | LOW (v5.0)
Specifies whether the operating system should attempt to load a part of itself into the HMA (HIGH) or keep all of the operating system in conventional memory (LOW). The default setting is LOW.
[NO]UMB (v5.0)
Specifies whether the operating system should manage upper memory blocks (UMBs) created by a UMB provider such as EMM386.EXE. The UMB parameter specifies that the operating system should manage UMBs, if they exist. The NOUMB parameter specifies that the operating system should not manage UMBs. The default setting is NOUMB.

Switches

none.


Related

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.


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=HIGH or DOS=UMB.


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, the operating system will not display an error message.


Using the HIGH parameter

If you specify the HIGH parameter, the operating system attempts to load part of itself into the HMA. Loading part of the operating system into the HMA frees conventional memory for programs. If you specify DOS=HIGH and the operating system 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. The following command lines are valid:

    DOS=UMB],LOW

    DOS=HIGH,UMB

You can place the DOS command anywhere in your CONFIG.SYS file.


Examples

none.


Errorlevels

none.


Availability
External
DOS
v5.0 v5.0A v5.00.02 v5.001A v5.01 v5.02 v6.0 v6.10 v6.2 v6.21 v6.22 v6.23 v7.00 v7.0R1 v7.10 v8.00
Windows
none
Windows NT
none