Browse Prior Art Database

Solution for Intercommunication between Protected Mode and Real Mode Programs

IP.com Disclosure Number: IPCOM000105866D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Long, DM: AUTHOR

Abstract

Disclosed is a software programming scheme that allows a Windows* Protected mode program to communicate with a Real mode DOS Device Driver using a Real mode Terminate-and-Stay-Resident (TSR) program.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 59% of the total text.

Solution for Intercommunication between Protected Mode and Real Mode Programs

      Disclosed is a software programming scheme that allows a
Windows* Protected mode program to communicate with a Real mode DOS
Device Driver using a Real mode Terminate-and-Stay-Resident (TSR)
program.

     When running in the Windows Protected mode environment, the
memory location of a program is not static but may be swapped from
location to location as the Windows system requirements change over
time.  This poses a problem for situations where a Real mode device
driver must be able to communicate with the Protected mode program
via an Application Programming Interface (API).

     The disclosed scheme uses a shared, real memory buffer (below
the one-megabyte boundary) in which all communication data is passed
between the Real mode device driver and Protected mode program.  This
buffer is defined by a small, TSR program which passes the buffer
address to the device driver via an API.  To complete the
communication path, the TSR program provides, upon request, the
buffer address to the Windows Protected mode program.  This request
is made via a standard software interrupt.

     Communication from the device driver to the Windows program
occurs as follows:

     1.)  The Real mode device driver calls the TSR Resident program
via
          an API.  This call contains a pointer to data that needs to
be
          processed by the Windows Protected mode pr...