Page 350 - DCAP103_Principle of operating system

Unit 11: Operating System Structure

3. The ...................... provides a framework for managing I/O devices and provides generic Notes
I/O services.
( a) I/O manager (b) I/O providers
( c) Device manager (d) Device provider

4. The ...................... keeps the most recently used disk blocks in memory to speed up access
to them in the event that they are needed again.

( a) Power manager (b) Memory manager
( c) Process manager (d) Cache manager

5. Device drivers are not part of the ...................... .
( a) Kernel binary (b) krnl.exe binary

( c) ntoskr.exe binary (d) ntoskrnl.exe binary

11.2 Summary

• Windows2000 consists of two major parts: the operating system itself, which runs in kernel
mode, and the environment subsystems, which runs in user mode.
• Hardware Abstraction Layer, the way it manages clocks and timers in a portable way.

• The Kernel Layer, which includes the control objects and dispatcher objects.
• Executive includes the object manager, I/O manager, process manager, memory manager,
security manager, cache manager, plug-and-play manager, power manager, configuration
manager, and local procedure call manager.
• Device drivers which control one or more I/O devices.

11.3 Keywords

Control Objects: These are the objects that control the system, including primitive process objects,
interrupt objects, and two somewhat strange objects called DPC and APC.

DirectX: HAL is reasonably efficient, for multimedia applications it may not be fast enough. For
this reason, Microsoft also produced a software package called DirectX. It allows user processes
much more direct access to the hardware.

Graphic Device Interface (GDI): It handles image management for the monitor and printers. It
provides system calls to allow user programs to write on the monitor and printers in a device-
independent way.

HAL (Hardware Abstract Layer): Microsoft made a serious attempt to hide many of the machine
dependencies in a thin layer at the bottom that is called HAL (Hardware Abstraction Layer).

System Services: At the top of the executive is a thin layer called system services. Its function
is to provide an interface to the executive. It accepts the true Windows 2000 system calls and
calls other parts of the executive to have them executed.

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