LMATUC03

LMATUC03 - 15 CHAPTER 1 Configuring Your System This...

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15 CHAPTER 1 This chapter describes how to configure your system for optimal use of MASM and explains the recommended modifications to your system files (CONFIG.SYS, AUTOEXEC.BAT, and SYSTEM.INI). This chapter also provides information on conventional memory, extended memory, expanded memory, and memory managers. This will help you: u make more memory available for MASM and other programs u optimize the speed at which your programs run u use the memory in your system more efficiently You may need to experiment with the described techniques to find the right optimization for your system. MS-DOS version 5.0 or later provides many new features that make memory configuration easier. Many of the recommendations made in this chapter require your system to have these new MS-DOS features. If you have not upgraded to MS-DOS version 5.0 or later, you may want to do so before configuring your system files for MASM. Understanding System Configuration Terminology This section defines terms that can help you understand the configuration infor- mation in this chapter. Figure 3.1 shows the relationship between the different memory areas. § Figure 3.1 Memory Locations Configuring Your System Note Filename: 1274b3c1b8683adb1d9a4dde82e6990720fd1122.doc Project: Template: Author: Last Saved By: Revision #: 0 Page: 15 of 30 Printed: 11/04/92 09:58 A11/P11
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Conventional (Real) Memory The first 640K of memory in a computer using an Intel-compatible processor. All MS-DOS systems have conventional memory. All application programs can use conventional memory without additional memory-management programs. Extended Memory Memory above the first 1 MB of memory on systems with 80286 or higher processors. Most 80386 computers come with some extended memory. Extended memory requires an extended memory manager, such as HIMEM.SYS, to prevent programs from using the same area of extended memory at the same time. You need nearly 3.5 megabytes of extended memory to run MASM on your system (4 megabytes of total system memory). High Memory Area (HMA) The first 64K of extended memory. Systems using MS-DOS version 5.0 or later can load MS-DOS into the HMA. This will free about 50K of conventional memory. Expanded Memory An area of memory accessible to programs that can access memory above 640K. Expanded memory is divided into 16K segments called “pages.” When a program requests information from expanded memory, an expanded memory manager “maps” or copies the appropriate page to an area called a “page frame” in upper memory. Since an expanded memory manager allows programs access to a limited amount of information at one time, expanded memory can be slower for programs to use than extended memory. Expanded memory requires special drivers such as EMM386.EXE. EMM386.EXE can also use extended memory to emulate expanded
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This note was uploaded on 01/24/2012 for the course EE 3751 taught by Professor Desouza during the Spring '04 term at LSU.

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LMATUC03 - 15 CHAPTER 1 Configuring Your System This...

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