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Unit 6: Memory Management (II)
know which functions suggest the traits best matched to your intention and precisely how much Notes
of a resource hit appears when using every function.
Self Assessment
Fill in the blanks:
10. The first version of the Windows operating system established a technique of managing
dynamic memory relying on a single ...................... heap, which all applications and the
system share, and several, private local heaps, one for every application.
11. The Windows API offers different levels of ...................... management for adaptability in
application programming.
6.3 System Memory and System Resources
Consider that you’ve got 4GHz Pentium IV with 1Gb of RAM and Windows 98. Still, applications
appear to be running out of memory. They run sluggishly, or you may obtain the dreaded
“Unable to create control” message, or poorer yet the whole operating system freezes up. What
is basically the problem?
The short respond resources. You’ve got gigabyte of RAM! The short respond: that makes no
dissimilarity. You add another 512Mb of RAM. Now you contain 1.5Gb of RAM. Still you have
the similar problem. The depressing truth is, the amount of physical memory has completely no
impact on system resources. When your system runs short on system resources awful things,
such as the foregoing, occur.
Notes While it appears to be picking on Windows98 here, the memory model is
fundamentally the similar in Windows95, Windows98 and Windows Me. Afterwards,
we’ll talk regarding WindowsNT and its successors Windows 2000 and WindowsXP, which
share a considerably dissimilar memory model.
6.3.1 What are System Resources?
The term System Resources essentially comprises two major areas of Windows memory that are
reserved for and used by particular Windows components. They are known as User and GDI.
User resources points to the input manager user32.dll. It manages input from your mouse,
keyboard, and other sources, like communication ports, file handles, etc. GDI symbolizes Graphics
Device Interface and is in accuse of the noticeable components of Windows. It accumulates fonts,
brushes, bitmaps, and other graphics stuff, in addition to lends support to other graphic output
devices like printers. On Windows 9x/Me systems, you can observe resources by means of the
resource monitor. It returns the amount of free resources as a percentage.
Under Windows 3.x, these two areas of memory were restricted to 64K. All running applications
shared that 64K for User resources and 64K for GDI. Unnecessary to say, that formed a huge
bottleneck.
With the foreword of Windows95 and enduring through Windows98 and WindowsMe, that 64K
was augmented dramatically and each of the two areas was further subdivided as follows:
The 16-bit User heap (64K).
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