MS DOS Command: MEM.EXE

Reference from Microsoft MS-DOS cmd help

Description

Displays the amount of used and free memory on your computer.

You can use the MEM command to display information about allocated memory areas, free memory areas, and programs that are currently loaded into memory.

Syntax

MEM [/CLASSIFY|/DEBUG|/FREE|/MODULE modulename] [/PAGE]

To display the status of your computer's used and free memory, use the following syntax:

MEM

Switches

/CLASSIFY	Lists the programs that are currently loaded into memory and shows how much conventional and upper memory each program is using. MEM /CLASSIFY also summarizes overall memory use and lists the largest free memory blocks. You can use the /CLASSIFY switch with /PAGE but not with other MEM switches. You can abbreviate /CLASSIFY as /C.
/DEBUG	Lists the programs and internal drivers that are currently loaded into memory. MEM /DEBUG shows each module's size, segment address, and module type, summarizes overall memory use, and displays other information useful for programming. You can use the /DEBUG switch with /PAGE but not with other MEM switches. You can abbreviate /DEBUG as /D.
/FREE	Lists the free areas of conventional and upper memory. MEM /FREE shows the segment address and size of each free area of conventional memory, and shows the largest free upper memory block in each region of upper memory. You can use the /FREE switch with /PAGE but not with other MEM switches. You can abbreviate /FREE as /F.
/MODULE programname	Shows how a program module is currently using memory. You must specify the program name after the /MODULE switch. MEM /MODULE lists the areas of memory the specified program module has allocated and shows the address and size of each area. You can use the /MODULE switch with /PAGE, but not with other MEM switches. You can abbreviate /MODULE as /M.
/PAGE	Pauses after each screen of output. This switch can be used with any of the other MEM switches.

Related Command

For information about checking the amount of space available on a disk, see the CHKDSK command.

Remarks

Specifying the /PAGE switch automatically

You can use the DOSKEY program to automatically add the /PAGE switch to the MEM command. Then, each time you use MEM, it will pause after each screenful of information even if you don't type the /P switch on the MEM command line. To do this, add the following commands to your AUTOEXEC.BAT file:

c:\dos\doskey

doskey mem=mem.exe $* /p

Displaying memory status

MS-DOS displays the status of extended memory only if you have installed memory above the 1-megabyte (MB) boundary in your system. MS-DOS displays the status of expanded memory only if you use expanded memory that conforms to version 4.0 of the Lotus/Intel/Microsoft Expanded Memory Specification (LIM EMS). MS-DOS displays the status of the upper memory area only if a UMB provider such as EMM386 is installed and the command DOS=UMB is included in the CONFIG.SYS file. MS-DOS does not display the status of the upper memory area if you issue the MEM command while you are running Windows version 3.0.

Allocating extended memory

To allocate Interrupt 15h memory and XMS memory at the same time, use the /INT15 switch when you load the HIMEM.SYS device driver.

For more information, see HIMEM.SYS.

Examples

Getting general program and memory information

Suppose your system has both expanded memory and extended memory. To display a summary of your system's total memory--conventional, expanded, extended, and upper--and to display a list of programs currently loaded into memory, type the following command:

mem /classify

The results might look similar to the following:

Modules using memory below 1 MB:

Name	Total		=	Conventional		+	Upper Memory
SYSTEM	16,477	(16K)		16,461	(16K)		16	(0K)
SETVER	784	(1K)		784	(1K)		0	(0K)
HIMEM	1,168	(1K)		1,168	(1K)		0	(0K)
EMM386	3,120	(3K)		3,120	(3K)		0	(0K)
USPI14	9,120	(9K)		9,120	(9K)		0	(0K)
COMMAND	3,680	(4K)		3,680	(4K)		0	(0K)
SMARTDRV	37,680	(37K)		21,280	(21K)		16,400	(16K)
MOUSE	17,088	(17K)		17,088	(17K)		0	(0K)
NETBEUI	42,432	(41K)		41,760	(41K)		672	(1K)
REDIR	86,064	(84K)		76,128	(74K)		9,936	(10K)
ANARKEY	14,384	(14K)		0	(0K)		14,384	(14K)
ZPOWER	4,368	(4K)		0	(0K)		4,368	(4K)
ANSI	4,208	(4K)		0	(0K)		4,208	(4K)
DRVSPACE	36,848	(36K)		0	(0K)		36,848	(36K)
PROTMAN	128	(0K)		0	(0K)		128	(0K)
EXP16	9,056	(9K)		0	(0K)		9,056	(9K)
WORKGRP	4,368	(4K)		0	(0K)		4,368	(4K)
RAMDRIVE	1,312	(1K)		0	(0K)		1,312	(1K)
Free	472,464	(461K)		464,448	(454K)		8,016	(8K)

Memory Summary:

Type of Memory	Total	=	Used	+	Free
Conventional	655,360		190,912		464,448
Upper	109,712		101,696		8,016
Reserved	393,216		393,216		0
Extended (XMS)	15,618,928		12,424,048		3,194,880
Total memory	16,777,216		13,109,872		3,667,344
Total under 1 MB	765,072		292,608		472,464

Largest executable program size	464,352	(453K)
Largest free upper memory block	7,888	(8K)
MS-DOS is resident in the high memory area.

"Reserved" is the memory located on add-on boards such as video adapter boards. "Largest executable program size" is the largest contiguous block of conventional memory available for a program. "Largest free upper memory block" is the largest area of upper memory available for a program. "MS-DOS is resident in the high memory area" indicates that MS-DOS is running in the first 64K of extended memory rather than in conventional memory.

Getting information about a specific program

To find out what memory a specific program module has allocated, use the MEM /MODULE command. For example, to find out what memory the WIN386 module has allocated, you would type the following command:

mem /module win386

If you were running WIN386, the results might look similar to the following:

WIN386 is using the following memory:

Segment	Region	Total		Type
0081D		80	(0K)	Data
02EF8		384	(0K)	Environment
02F10		89,856	(88K)	Program
0D4D0	1	96	(0K)	Data
0D611	1	7,888	(8K)	Data
0EFFE	2	32	(0K)	Data
Total Size:	98,336	(96K)

Some program modules, such as WIN386, allocate more than one area of memory. The MEM /MODULE command displays all the areas of memory allocated by the specified program, and shows the segment address and size of each allocation. For upper memory blocks, MEM /MODULE also shows the region number. The Type column shows how the program is using that particular area of memory. The "total size," in this case 98,336 bytes (96K), shows the total amount of memory allocated by MS-DOS for the specified program.