Page 402 - DCAP103_Principle of operating system

Unit 13: Input/Output and Security of Windows

in which one process opens some file for reading and writing and a second process maps that Notes
file onto its address space. What happens if the second process writes on the file directly and
immediately thereafter the first one reads in a block that was just changed? Does it get stale
data? The answer is no. In both cases open files and mapped files, the cache manager maps a
256 KB piece of its virtual address space onto the file. The file is only mapped once, no matter
how many processes have it open or mapped. In the case of a mapped file, both the cache
manager and the user process share pages in memory. When a read request has to be satisfied,
the cache manager just copies the page from memory to the user buffer, which always reflects
the exact current state of the file because the cache manager is using the same pages as the
process that has the file mapped in.

Before installing the operating system the customer setting and the data base
have to be saved.

Self Assessment

Fill in the blanks:

5. In a file, encryption is done by a driver called ...................... .
6. The Windows 2000 cache is organised by ...................... block.

7. ...................... hard disk drive is a non-volatile, random access device for digital data.
True or False:

8. The zip drive is a medium-capacity removable disk storage system.
9. SIDs are binary numbers with a short header followed by a long random component.

13.5 Summary

• The I/O manager is on intimate terms with the plug-and-play manager. The basic plug
and play is that of an enumerable bus.

• Microsoft has defined a Windows Driver model that device drivers are expected to conform
with.

• Windows 2000 supports some important files like FAT-16, FAT-32 and NTFS.
• Secure login means that the system administrator can require all user to have password
in order to log in.
• Win32 API security calls relate to the management of security descriptors.

• The caches manager jobs keep file systems blocks that have been used recently in memory
to reduce access time on any subsequent reference.

13.6 Keywords

Bitmaps: Bitmap or pixmap is a type of memory organization or image file format used to store
digital images.

Dynamic Disks: The Dynamic Disk is a physical disk that manages its volumes by using LDM
database.

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