Logical memory is the way physical memory is seen by the operating system. The MS-DOS memory map shows the first 640KB of RAM as the user (conventional) area and the rest of the first megabyte of RAM as reserved for the computer’s needs. The user area is the problem area for DOS users because DOS uses some of the conventional memory as you load applications or add new hardware drivers. As conventional memory is used, programs that have been running may report insufficient memory when they are next executed. The usual solution to this problem is to optimize memory.
You can optimize DOS memory usage manually by modifying the AUTOEXEC.BAT and CONFIG.SYS files or using the MEMMAKER utility. DOS experts can do a better job of optimizing memory than the MEMMAKER utility, but the number of DOS experts is in decline. For most situations, running MEMMAKER yields satisfactory results.
Upon completion of this lab, you will be able to:
Determine memory usage in a DOS system
Optimize memory in a DOS system
For this lab, you will need a working computer with DOS 6.x installed.
In this lab, you will examine DOS memory utilization. You will also free up additional conventional memory by optimizing DOS memory with the MEMMAKER utility.
To examine DOS memory usage,
Boot the computer to drive C:.
Run the MEM utility to display the current memory utilization:
C:\>MEM
Record the memory information from the MEM utility in Table 2.1.
Memory Type | Total | Used | Free |
---|---|---|---|
Conventional | _______KB | _______KB | ___________KB |
Upper | _______KB | _______KB | ___________KB |
Reserved | _______KB | _______KB | ___________KB |
Extended (XMS) | _______KB | _______KB | ___________KB |
Total memory | _______KB | _______KB | ___________KB |
Total under 1MB | _______KB | _______KB | ___________KB |
Largest executable-program size | _______KB | ||
Largest free upper-memory block | _______KB |
To optimize DOS system memory with the MEMMAKER utility,
Enter the following command to optimize the DOS memory with the MEMMAKER utility:
C:\>MEMMAKER
Accept the default conditions as the program runs.
If the computer fails during the MEMMAKER utility, warm-boot the computer, run MEMMAKER again, and choose Try Again with Conservative Settings.
If the computer is unable to boot after MEMMAKER runs, boot to a DOS utility disk and enter the following command to undo the optimization:
C:\>MEMMAKER /UNDO
After MEMMAKER has finished optimizing the system’s memory and reboots the computer, run the MEM utility again:
C:\>MEM
Record the memory information from the MEM utility in Table 2.2.
Memory Type | Total | Used | Free |
---|---|---|---|
Conventional | ________KB | __________KB | __________KB |
Upper | ________KB | __________KB | __________KB |
Reserved | ________KB | __________KB | __________KB |
Extended (XMS) | ________KB | __________KB | __________KB |
Total memory | ________KB | __________KB | __________KB |
Total under 1MB | ________KB | __________KB | __________KB |
Largest executable-program size | ________KB | ||
Largest free upper-memory block | ________KB |
Compare the conventional memory usage listed in Table 2.1 with that listed in Table 2.2. If the Free amounts in Table 2.2 are greater than those in Table 2.1, the optimization was successful.