Meet 3-4 Flashcards
- It gather together multiple CPUs to accomplish computational work.
- They are composed of two or more individual systems coupled together.
- Provide high availability
- Can be structure asymmetrically or symmetrically
Clustered Systems.
Two things that every OS must be capable of doing.
- Multiprogramming
- Time Sharing (Multitasking)
The capability of running multiple programs by the CPU.
Multiprogramming
Increases the CPU utilization by organizing jobs (code and data) so that the CPU always has one to execute.
Multiprogramming
- The CPU executes multiple jobs by switching among them.
- Switches occur so frequently that the user can interact with each program while it is running.
- This requires an interactive (or hands-on) computer system, which provides direct communication between the user and the system.
Time Sharing (Multitasking)
- Uses CPU scheduling and multiprogramming to provide each user with a small portion of the time-shared computer.
- Each user has at least one separate program in memory.
Time Sharing (Multitasking)
A program loaded into the memory and is executed is called
Process
Human to computer interaction and communication in a device. Ex. CLI, GUI
User Interface
CLI stands for
Command Line Interface
GUI stands for
Graphical User Interface
Run the program in the computer
Program Execution
Transfers data to or from a computer
I/O Operations
- The OS controls how the files in your system are manipulated or managed.
- It also controls the permission that is given to certain programs or users for the access of certain files.
File System Manipulation
Process of exchanging information between different components of an OS
Communications
When errors occur, your systems must not break down completely and it should not just seize your computing ability completely.
Error Detection
- The OS should allocate the required resources to the process which are asking for those resources.
- The OS must allocate the resources in an efficient way such that all the processes get the resources that they need.
Resource Allocation
Having usage statistics can be valuable for researchers who wish to reconfigure the systems or to improve the computing services.
Accounting
When several different processes are executing at the same time, they should not interfere with each other’s operation. And protection involves ensuring that all access to system resources are controlled.
Protection and Security
9 Operating System Services
- User Interface
- Program Execution
- I/O Operations
- File System Manipulation
- Communications
- Error Detection
7.Resource Allocation - Accounting
- Protection and Security
Provides an interface to the services made available by an Operating System.
System Calls
Two modes of operation on which a program can execute.
- User Mode
- Kernel Mode
- Does not have direct access to memory, to the hardware and the others resources.
- Safe Mode
User Mode
- Has direct access to memory, hardware and other resources.
- Privileged Mode
Kernel
When a program is switching from user mode to kernel mode (vice versa) that is known as
Context Switching
5 Types of System Calls
- Process Control
- File Manipulation
- Device Management
- Information Maintenance
- Communications
- end, abort
- load, execute
- create process, terminate process
- get process attributes, set process attributes
- wait for time
- wait event, signal event
- allocate and free memory
Process Control
- create file, delete file
- open, close
- read, write, reposition
- get file attributes, set file attributes
File Manipulation
- request device, release device
- read, write, reposition
- get device attributes, set device attributes
- logically attach or detach devices
Device Management
- get time or date, set time or date
- get system data, set system data
- get process, file, or device attributes
- set process, file, or device attributes
Information Maintenance
- create, delete communication connection
- send, receive messages
- transfer status information
- attach or detach remote devices
Communications
also known as system utilities, provides a convenient environment for program development and execution.
System Programs
6 Categories of System Programs
- File Management
- Status Information
- File Modification
- Programming-language support
- Program loading and execution
- Communications
- Create
- Delete
- Copy
- Rename
- Dump
- List and generally manipulate files and directories.
File Management
Ask the system for:
- Date, Time
- Amount of availability memory or disk space
- Number of users
- Detailed performances
- Logging and debugging information
Status Information
- Several text editors may be available to create and modify the content of files stored on disk or other storage devices.
- There may also be special commands to search contents files or perform transformations of the text.
File Modification
- Compilers
- Assemblers
- Debuggers
- Interpreters
Programming-language support
Once a program is assembled or compiled, it must be loaded into memory to be executed.
The system may provide: (4)
Program loading and execution
- Absolute loaders
- Relocatable loaders
- Linkage editors
- Overlay loaders
These programs provide the mechanism for:
- Creating virtual connections among processes, users, and computer systems.
- Allowing users to stand messages to one another’s screens
- To browse Web pages
- To send electronic-mail messages
- To log in remotely, and to transfer files from one machine to another.
Communications
The system should be convenient to use, easy to learn and to use, reliable, safe, and fast.
User Requirement (User Goals)
The system should be easy to design, implement, and maintain; and it should be flexible, reliable, error free, and efficient.
Designer/Engineer Requirements (System Goals)
It determines how to do something
Mechanism
It determine what will be done
Policies
Advantages of writing in high level languages (4)
- The code can be written faster
- It is more compact
- It is easier to understand and debug
- It is easier to port
