Category : Alternate Operating Systems - Quarterdeck DesqView, CP/M, etc
Archive   : QWHITE13.ZIP
Filename : MEMSTAT.TEC

 
Output of file : MEMSTAT.TEC contained in archive : QWHITE13.ZIP

ID:MS Memory Status Discussion
Quarterdeck Technical Note #131 Filename: MEMSTAT.TEC
by Bob Perry CompuServe: MEMSTA.TEC
Last revised: 3/09/92 Code: DV

Subject: An explanation of the information provided by DESQview's Memory
Status program, and how this information relates to your ability to
multitask large applications.


Q. What do the numbers in the Memory Status window mean?

Q. Why does DESQview report 0K for Largest Available Expanded Memory?

Q. Why does Total Memory for Expanded not report all my board memory?

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 numbers.

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 caches.

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.

************************************************************************
*This technical note may be copied and distributed freely as long as it*
*is distributed in its entirety and it is not distributed for profit. *
* Copyright (C) 1991 by Quarterdeck Office Systems *
************************ E N D O F F I L E *************************