- 1. Operating Systemand Utility Programs Chapter 2 B.M.H
2. Computer System
-
- Storage (secondary storage)
MIU 3. Learning Objectives
- OS for large computer systems
-
- The method of resource allocation
MIU 4. Mainframes
- Large, fast and fairly expensive computers
- Used by business or governmentto provide centralized
storage
- EX) IBM 4381, 9300, 3090, Cyber 180
MIU 5. MIU 6. OS for large computers
- Large computer - mainframes
-
- Around about twice as long as PCs
-
- Owned by businesses and universities
-
- Used by many people at once
-
- Present special (sharing) problems
-
-
- Program, CPU, memory, storage, printer
- OS : take care of these things behind the scenes
-
- So that User can share the computer s resources
MIU 7. Resource Allocation
-
- (Allocate : give something to somebody for special
purpose)
-
- : the process of assigning computer resources to certain
programs
MIU 8. Resource Allocation
- SharingPrinting Resources
MIU 9. Sharing the CPU
- Most computers have a single CPU.
-
- All programs must share it.
-
- Two approaches to sharing
MIU (Resource allocation) 10. Multiprocessing
- The use of a powerful computer withmultiple CPUs
- Multiple programs can runsimultaneously , each using its own
processor
MIU (Resource allocation) 11. Multiprogramming
- Onlyone Central Processing Unit
- Two or more programs are executed in the same time
frame,concurrently
-
- But not exactly at the same instant
-
- Taking turns ; one program runs for a while, and then another
one runs
-
- Programs share resources based on events that take place in the
programs.
MIU (Resource allocation) 12. Multiprogramming
- Implemented by OS through a system of interrupts
-
-
- A signal that causes normal program processing to be suspended
temporarily.
MIU 13. Time-Sharing
- A special case of multiprogramming
-
- To give each user a time slice
-
- The OS doesn t wait for completion of an event
-
-
- At the end of the time slice, the resources are taken away from
the user and given to someone else
MIU (Resource allocation) 14. Sharing Memory
-
-
- allocating memory to programs and
-
-
- keeping the programs in memory separate from one another
-
-
- Foreground and background
MIU (Resource allocation) 15. Partitions
- Some systems simply divide memory into separate areas
(partitions or regions)
-
- Each of which can hold a program
MIU Sharing Memory 16. Foreground and Background
- Large all-purposed computers divide the memory into foreground
and background
- In a time-sharing environment
-
-
- For programs that havehigher priority
-
-
- : Interactive program (with the user at a terminal awaiting
response)
-
-
- For programs with less pressing schedules
-
-
- lower prioritiesand less CPU time
MIU Sharing Memory 17. Virtual Storage (1)
- Many computer systems uses this technique
-
- Virtual : made to appear to exist by the use of computer
SW
- The programs currently being executed are stored ondisk ,
- portions of these programs
-
- are brought intomemoryas needed.
-
- Secondary storage : virtual storage
MIU Sharing Memory 18. Virtual Storage (2)
-
- one way of virtual storage
-
-
- dividing a program into equal-size pieces
-
-
- storing them in equal-size memory spaces
-
- All pages and page frames
-
-
- : the same fixed size (ex. 2 or 4 KB)
MIU Sharing Memory Refer to Fig 2-11 19. Sharing Storage
Resources
- More than user want to read or write a record
-
- from the same disk pack at the same time
-
- Keeps track of which file is where
-
- Responds to commands to manipulate files
-
- Keeps track of the Input and output requests
-
-
- In the order in which they were received
-
- Routes any program instruction to read or write a record
MIU Resource allocation 20. Sharing Printing Resources
-
- A process for sharing a printer
-
-
- Moving data and store it for a short time on adiskbefore it is
printed
-
-
-
- Each program writes onto a disk each line that is to be
printed
-
-
- The disk file is placed into aqueue
-
-
- It is printed when the printer becomes available
MIU Resource allocation 21. Utility Programs File Manager Back
up and Restore File Compression Defragmenter Device Drivers 22.
Utility Programs (1)
- Most of the resource allocation tasks
-
- : done by the OS without user involvement
-
- : perform explicit servicesat the user s request
-
- Utility : a piece of computer SW that performs a particular
task
-
- Part of the system software, not part of the OS.
-
- Some utilities are packaged with OSs
-
- Others can be purchased separately
MIU 23. Utility Programs (2)
- To avoid duplication of effort
-
- Compressing files and entire hard disks
-
- Searching computer viruses
MIU 24. File manager (1)
- Organize and manage files in a hierarchical directory
structure
-
- organized in a way that makes sense to you
-
-
- : a named area in storage that can contain files and other
directories
-
-
- The newer versions of Windows
-
-
-
- : Refer to directories asfolders
MIU Utility Programs 25. File manager (2)
-
- Enable you to create the directory structure
-
- Display lists of files in directories
-
-
- ; to copy, move, rename, and delete files
-
-
- ; and to format and copy diskettes
MIU Utility Programs 26. Back up and Restore
- Make backups of entire hard drives or of selected
directories
-
- Backing up files involves
-
-
- Storing them in a safe place
-
- These backups could be made to
-
-
- Diskettes, high capacity media (CD, tape)
- Create the backup files in a specific format to minimize space
requirements
- Needed the restore routine to use them
MIU Utility Programs 27. File Compression
- Reduces the amount of space of a file
-
- Take up less space on disk
-
- Take less time to transmit across communication line
-
- Must be uncompressed into their original form before using
them
MIU Utility Programs 28. Defragmenter
- Reorganize the files on the disk
-
- so that all files are stored incontiguous locations
-
- Ex) Windows : Disk Defragmenter
-
- Fragmented: noncontiguous storing because of not enough
space.
MIU Utility Programs 29. Device Drivers (1)
- Allow the OS to communicate with peripherals
-
- Accepts standard commands from the OS
-
- Converts them into the proper format
-
- for the device it supports
MIU Utility Programs 30. Device Drivers (2)
-
- Providedevice driversfor their products
-
- : includes copying the appropriate driver to your hard
drive
MIU Utility Programs