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Lecture 1 |
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Introduction To Operating |
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Systems |
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An operating system is a program, or a set
of programs, that manages the operation of the computer. |
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An operating system is a program, or a set
of programs, that manages the operation of the computer. |
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DOS |
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Windows |
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UNIX |
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Linux |
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MacOS |
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There are many variants of each |
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E.g. Windows 9x/ME/NT/2000/Xp |
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Operating Systems manage computer systems. |
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Super-Computers |
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Mainframes |
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Mini-Computers |
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Micro-Computers (desktop PCs) |
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Embedded systems (TVs, VCRs, Missiles etc.) |
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Specialist systems (Medical Equipment etc.) |
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Different systems require different operating
systems. |
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The OS provides simplified access to the system
hardware. |
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User and Software interact with OS NOT the
hardware. |
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Software can therefore be hardware independent. |
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Resource Allocation & Scheduling |
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Memory Management |
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Backing Store Management |
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I/O Control |
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Interrupt Handling |
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User Interface Handling |
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Security |
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Accounting Facilities (User Accounts!) |
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Provision of Utilities |
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Main Storage |
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RAM |
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ROM |
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Secondary Storage |
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Hard Disk(s) |
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Floppy Disk(s) |
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CD / DVD / CD-RW |
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CPU |
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I/O Devices |
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One of the most Important OS tasks is that of
File Management. |
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Must be able to identify disks |
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A: Floppy Disk Drive |
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B: Second Floppy Disk Drive |
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C: Hard Disk |
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D: (Usually) CD / DVD Drive |
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Data is stored on the computer as files. |
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There may be literally thousands of files on a
computer disk. |
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There are different types of file – |
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System file |
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Data file |
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Program file |
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The files stored on the disk must be organised
in some fashion. |
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A disk has a file system to store the files
within. |
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Different operating systems (generally) have
different types of file system. |
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Win9x – FAT 16 or FAT 32 |
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WinNT – NTFS |
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These will be discussed later. |
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We must be able to do certain tasks: |
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Allow user to organise the files to make
location of them easier. |
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Prepare and/or repair the file system as needed. |
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Remove files from the disk |
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Move and Copy files |
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View the contents of files (sometimes) |
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Use files |
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The OS provides facilities to achieve these
tasks. |
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Used to organise files within the file system. |
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Also called FOLDERS |
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Like “real” folders, they store related files |
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Folders can be stored inside other folders. |
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This creates a hierarchical file-system |
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The file system’s starting point. |
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Denoted by the character \ |
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Each drive has a Root directory |
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A:\ The floppy disk’s root |
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C:\ The hard disk’s root |
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D:\ The CD (or DVD) root |
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Individual files are unique |
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A file’s name (within a directory) should be
unique |
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3 Character Extension – in both DOS and Windows |
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Format: |
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filename.extension |
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DOS: 8
Chars Max, no spaces |
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Win 3.11: As above, why? |
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Win 9x/2000/Xp: 256 chars, spaces allowed |
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Certain characters can’t be used: |
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? * |
\ / <
> “ |
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Look up UNIX and MacOS on Internet |
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3 Character Extension – in both DOS and Windows. |
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Some operating systems allow longer extensions. |
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Extension Describes the file contents. |
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In Win9x/2000/Xp, extension links the file to
its application executable. |
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TXT – Text File |
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DOC – Word Document |
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XLS – Excel Spreadsheet |
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PAS – Pascal File |
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C – C Programming File |
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ASM – Assembly Source File |
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BAT – Batch File |
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SYS – System File |
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dir View contents of directory |
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cd Change directory |
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md Make directory |
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rd Remove a directory |
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del Delete a file |
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format Format a disk |
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Often a parameter must be present for the
command to work as required. |
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Notes