KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q46774: Calculating an Application’s Load Size, Minimum Load Size

Article: Q46774
Product(s): Microsoft Programming Utilities
Version(s): 
Operating System(s): 
Keyword(s): kb16bitonly
Last Modified: 08-OCT-1999

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft LINK for MS-DOS 
-------------------------------------------------------------------------------

The MS-DOS program loader uses the following information to calculate
the number of 16-byte paragraphs to use when loading a program:


  Name in EXEHDR Output      Offset in .EXE Header
  ------------------------------------------------
  Bytes on Last Page                 2h-3h
  Pages in File                      4h-5h
  Paragraphs in Header               8h-9h
  Extra Paragraphs Needed            Ah-Bh
  Extra Paragraphs Wanted            Ch-Dh

Given the information in the table above, compute the load size as
follows:

  Load Size = Bytes on Last Page * (1 paragraph / 10h bytes)

  + Pages in File * (20h paragraphs / page)
  + 10h - Paragraphs in Header
  + Extra Paragraphs Wanted

The Load Size is the number of 16-byte paragraphs requested. If not
enough memory is available, the application receives all available
memory. However, if the memory available is not greater than or equal
to the Minimum Load Size, MS-DOS cannot load the program. Compute the
Minimum Load Size as follows:

  Minimum Load Size = Bytes on Last Page * (1 paragraph / 10h bytes)

  + Pages in File * (20h paragraphs / page)
  + 10h - Paragraphs in Header
  + Extra Paragraphs Needed


The value 20h is the size, in paragraphs, of one page, (512 / 16). The
value 10h is the size, in paragraphs, of the 256-byte Program Segment
Prefix (PSP) that precedes each program in memory.

For more information, please refer to an MS-DOS reference like the
"MS-DOS Encyclopedia" (Microsoft Press), page 124.

Additional query words: kbinf 3.00 3.60 4.10 5.10 5.30 5.50

======================================================================
Keywords          : kb16bitonly 
Technology        : kbAudDeveloper kbZNotKeyword3 kbLINKSearch
Version           : :

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.