Operating Systems: Chapter 2

User Interface

Some way of providing commands to the operating system

Program Execution

The system's ability to load a program into memory and to run that program

I/O Operations

Giving a running program access to required I/O

File-System Manipulation

Giving a program access to read

Communication

The exchange of information between two processes

Error Detection

For each type of error the operating system can take the appropriate action to ensure correct and consistent computing

Resource Allocation

When there are multiple users or jobs running at the same time

Accounting

Keeping track of which users use how much and what kinds of computer resources

Protection and Security

The owners of information stored in a multiuser or networked computer system may want to control use of that information

Command Interpreter

A user interface that allows users to directly enter commands to be performed by the operating system

Shells

One interpreter in a system with multiple command interpretters

System Calls

Provide an interface to the service made available by an operating system

Application Programming Interface (API)

A set of functions that are available to an application programmer

Run-time Support System

A set of functions built into libraries include with a compiler

System-Call Interface

The link to system calls made available by the operating system

Debugger

A system program designed to aid the programmer in finding and correcting bugs

Shared-Memory Model

Processes use system calls to create and gain access to regions of memory owned by other processes

What is the hierarchy of a logical computer?

• Hardware

• Operating System

• System Programs

• Application Programs

System Programs/System Utilities

A convenient environment for program development and execution

File Management

Programs which create

Status Information

A program which asks the system for simple or complex information about the system

Registry

A system used to store and retrieve configuration information

File Modification

Special commands to search contents of files or perform transformations of the text

Programming-Language Support

Compilers

Program Loading and Execution

Once a program is assembled

Communications

Programs which provide the mechanism for creating virtual connections among processes

Application Programs

Programs that are useful in solving common problems or performing common operations

User Goals for Developing an Operating System

• Convenient to use

• Easy to learn

• Reliable

• Safe

• Fast

System Goals for Developing an Operating System

• Easy to design/implement/maintain

• Flexible

• Reliable

• Error free

• Efficient

Mechanism

Determining how to do something

Policy

Determining what will be done

Emulator

A program that duplicates the functionality of one system in another system

Layered Approach

When an operating system is broken into a number of layers

What is the benefit of the layer approach?

A single layer can be debugged without worry about the layers above it. Similarly when debugging a layer it can be assumed that the layers below it are assembled correctly without error

Microkernel

A method which structures the operating system by removing all nonessential components from the kernel and implementing them as system and user-level programs

Virtual Machine

Abstracting the hardware of a single computer into several different execution environments

What are the benefits of using a virtual machine?

• The host system is protected from the virtual machines

• They are beneficial for operating system research and development

• Multiple operating systems can be running on a developer's workstation concurrently

Consolidation

Taking two or more separate systems and running them in virtual machines on one system

Simulation

When the host system has one system architecture and the guest system was compiled for a different architecture

Para-virtualizaiton

Rather than try to trick a guest operating system into believing it has a system to itself

Log File

A file containing error information to alert system operators that a problem occurred

Core Dump

A capture of the memory of the process

Crash

A kernel failure

Crash Dump

Error information is saved to a log file

Profiling

Periodically samples the instruction pointer to determine which code is being executed

System Generation (SYSGEN)

A system must be configured or generated for each specific computer site

Bootstrap Program/Bootstrap Loader

A small piece of code that locates the kernel

Boot Block

A piece of code that can load an entire operating system into memory and begin its execution