Operating Systems Quiz 1 Review

operating system

a program that acts as a middle ground between the user of a computer and the computer hardware

Role of OS in Memory Management

It is responsible for tracking memory usage, allocating space to active processes, and deallocating space as needed

Role of OS in Device Management

It is responsible for hiding details of hardware devices from the user

Role of OS in File Management

It is responsible for creating and deleting files and directories, having primitives to manipulate files and directories, mapping files into secondary storage, and backing up files onto stable storage media

Role of OS in Process Management

It is responsible for creating and deleting user and system processes, suspending and resuming processes, and providing mechanisms for process synchronization, process communication, and deadlock handling

Role of OS in Security and Protection

It is responsible for any mechanisms that control access of processes or users to resources defined by the OS and the defense of the system against internal and external attacks

Interrupts / Why are they Important for OS function?

An interrupt is how the device controller informs CPU that an operation is completed. It is important for function because it allows the CPU to multitask and run multiple processes without constant polling

Memory (needed by running programs)

only large storage media that CPU can directly access

CPU Time (needed by running programs)

total amount of time spent by CPU to execute a process

I/O Devices (needed by running programs)

hardware that allows a user to interact with a computer

Multitasking

It has the CPU switch through jobs frequently allowing for interactive computing

Multiprogramming

It organizes jobs via job scheduling so the CPU always has one to execute

Dual-Mode Execution

It allows the system to protect itself by splitting its operations into user mode and kernel mode. It is important for system security and stability.

User-Mode

restricted privileges for user applications.

Kernel-Mode

full privileges to hardware and system resources.

Trees in OS Systems

used for process scheduling and organizing files

Linked Lists in OS Systems

used for managing processes and tracking free memory for allocation

Bitmaps in OS Systems

using for tracking resources

Hash Tables in OS Systems

fast lookups

Examples of Services Provided to Users/Programs by the OS

user interface, program execution, I/O operations, file management, process communication, and error detection

Examples of OS User Interfaces (UI)

command line (CL), touchscreen, graphics user interface (GUI)

System Calls and Services Provided to User Programs

It provide a programming interface to the services provided by the OS. Services include: process control, file management, device management, information maintenance, communications, and protection

Tightly Coupled vs Loosely Coupled System

A tightly coupled (monolithic structure) system could have changes to one part impact other parts. A loosely coupled system (layered approach) is made up of smaller, separate components with specific and limited functionality.

Monolithic Kernel

fast but tightly coupled, difficult to implement and extend, and can cause problems with one component to affect others.

Layered Kernel

loosely coupled, more simply constructed, and easier to debug but defining the specific functionality of each layer can be difficult.

Microkernel

smaller kernel, easier to port, easier to extend, and are generally more reliable/secure but its performance can suffer from the user space to kernel space communication

Why is separating mechanism from policy important? Example

Policies determine what will be done and Mechanisms determine how to do something. The separation is important because it allows flexibility if decisions are later changed.

Ex. Policy: Interrupt every 30 seconds

Mechanism: timer

Edit: change 30 t0 60

Preferred langauges for OS implementation

C and MIPS Assembly