Browse Prior Art Database

Method for Determining Available Free Memory

IP.com Disclosure Number: IPCOM000115523D
Original Publication Date: 1995-May-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Schmitt, J: AUTHOR [+3]

Abstract

Disclosed is a method for obtaining the location and size of the non-system memory requirements of a personal computing system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 69% of the total text.

Method for Determining Available Free Memory

      Disclosed is a method for obtaining the location and size of
the non-system memory requirements of a personal computing system.

      Adapters in a personal computing system need a certain amount
of memory to execute their unique functions.  This memory, called
non-system memory, is allocated from the total physical memory within
the system but is not managed or allocated by the primary operating
system.  This memory includes provisions for memory-mapped I/O
devices, memory on adapters which can be directly modified by the
adapters, and memory which can be relocated within its address space,
such as bank-switched and Expanded Memory Specifications (EMS)
memory.  The remaining memory, called system memory, is used for the
operating system and application programs.

      The presently-disclosed method provides a common method by
which the operating system can determine the size and location of
non-system memory.  This information may be used to determine whether
there is enough memory space remaining for program execution.  This
method is a programming interface extension to the Basic Input/Output
System (BIOS) code of the system.  The BIOS System Services INT 15H
(hexadecimal), function (AH)=C7H--Return Memory-Map Information is
extended in the following manner (with registers shown in
parentheses):
  Input:
    (DS:SI)-  Pointer to the user-supplied memory-map
               table with...