ID:MS Memory Status Discussion
Quarterdeck Technical Note #131
by Bob Perry
Q. What do the numbers in the Memory Status window mean?
Q. Why does DESQview report 0K for Largest Available Expanded
Q. Why does Total Memory for Expanded not report all my board
The Memory Status (MS.COM) program dynamically displays the
current memory usage of your system at any given moment. It
takes about 7K "overhead" to run this program. When you run
Memory Status, the window shows three columns and three rows of
The ROWS list the three main memory areas of interest:
1-Common Memory (in Bytes): Common Memory refers to the amount
of memory in DESQview's Common Memory buffer, and generally
should not be allowed to drop below 1,000 bytes. Allocations are
made by running the SETUP program.
2-Conventional Memory (in Kilobytes, K): Conventional Memory
refers to the memory available for you to run programs in the
0K-640K memory area of your computer. This consists of any type
of memory your system uses to fill out to 640K.
3-Expanded Memory (in Kilobytes, K): Expanded Memory refers to
memory supplied by expanded memory boards. Memory Status will
not report expanded memory used for other purposes, such as to
fill-out conventional memory, RAM disks, print spoolers or disk
The COLUMNS in Memory Status are useful in determining the
current memory sizes of the following three areas:
A. Total Memory: Total Memory refers to the total memory
available on your system at the moment you started DESQview.
Such things as device drivers, memory-resident programs and
buffers (indeed, almost everything you might load in your
CONFIG.SYS and AUTOEXEC.BAT files before DESQview) will cause the
numbers in this column to be lower.
B. Total Available: Total Available is the total memory
available to store data and run programs at the current moment.
These numbers are TOTAL numbers and do not reflect the size of
any one program, which is shown in the third column.
C. Largest Available: The third column, and perhaps the most
useful one, tells you the largest area of contiguous memory
available at the current moment to run a program. NOTE THAT YOU
MUST SUBTRACT APPROXIMATELY 14K FROM THESE FIGURES TO ADD OR
CHANGE A PROGRAM'S MEMORY SIZE. This is because DESQview needs
about 14K to manage each application.
The Largest Available amount of memory for Expanded Memory,
which is the lower right corner figure in Memory Status, is
useful because it determines the size of secondary programs that
you can multitask (i.e., keep running at the same time as your
conventional memory program) without swapping. Only expanded
memory which conforms to EEMS (Enhanced Expanded Memory
Specification) or EMS 4 (Expanded Memory 4.0 Specification) will
result in a number in this location. No other expanded memory
boards or boards with so-called EMS 4 software drivers can be
used for multitasking.
Copyright (C) 1991 by Quarterdeck Office Systems
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