Operating Systems Advanced OS - E

OS Advanced Evaluating an Operating System

OS Advanced Criteria for Evaluating Throughput – Total Execution Time/Total Elapsed Time Turnaround – Elapsed time between job submission & job completion Response Time – Elapsed time between a request for the computers attention and the computers response

OS Advanced Criteria for Evaluating Cont’d AvailabilitySecurityReliabilityCost Ease of Use

OS Advanced The ideal OS for a particular installation is a function of its application mix Or what programs you intend to run on the hardware available

OS Advanced Early computer users where termed “Hackers” They enjoyed fooling around with computers to see what they could do and how fast they could make them run

OS Advanced Today we still have “Hackers”, but it usually refers to someone who tries to break into computer systems to see what they do

OS Advanced MS-DOS Once the world’s most commonly used microcomputer operating system with over $ 50 billion in sales

OS Advanced MS-DOS A command driven OS command.com = Dos Shell io.sys = physical I/O msdos.sys = logical I/O

OS Advanced Each physical device attached to the computer must have a Device Driver A small piece of software code that allows the OS and hardware to communicate

OS Advanced File System Disk space is allocated in Clusters Each Cluster holds 1024 bytes or 2 sectors The Clusters are numbered sequentially starting at Zero and stored in the File Allocation Table

OS Advanced Interrupts are handled by the Interrupt Vector Table, and are generated continuously when we use computers, every key press initiates a interrupt

OS Advanced Windows 2000/XP Evolved from Windows NT

OS Advanced Multithreading Multiple applications are managed by the OS

OS Advanced Multitasking Multiple applications are run concurrently

OS Advanced Multiprocessing Multiple CPU’s used by the OS

OS Advanced Dynamic Disks The OS treats the whole Hard Drive as a single partition, that can be sub-divided to create any number of logical partitions called Volumes

OS Advanced FAT32 & NTFS File Management File Allocation Table 32 (FAT32) NT File System (NTFS)

OS Advanced NTFS uses the MFT or Master File Table to access the disk The MFT is a master directory NTFS accesses objects instead of byte streams as DOS and Unix do

OS Advanced NTFS enables file recovery due to system crashes or disk failure

OS Advanced Win2k & WinXP Utilize the Windows Driver Model (WDM) Allows Microsoft OS’s to share device drivers between different windows versions

OS Advanced Win2k & WinXP Use the Registry – a hierarchical database used to keep track of hardware and software settings within the computer

OS Advanced Registry In Windows XP the files that make up the Registry are stored in your %SystemRoot%\System32\Config directory. But you don’t want to modify or even open any of the files located in that directory.

OS Advanced Registry Files default security software system sam

OS Advanced All of these individual files combine to form the Registry. NEVER DELETE OR DIRECTLY EDIT THESE FILES Always use regedit.exe if you need to make a change in the Registry

OS Advanced Questions?