SLR 4

Question	Answer
What is a operating system + examples	The low-level software that does the basic computers function such as scheduling tasks and controlling peripherals. Microsoft Windows Apple IOS Google Android
What is a Operating System good at?	What process is to be executed next Allocating and managing memory Using device drivers to talk with devices Operating system provide a framework Using protocols to other machines Accepting and denying Security requests User interface is fairly easy to understand
What is layering?	Layers of a computer that only care about the layers above below them The layers are: User Applications Operating System Hardware
What is Paging?	Paging is processes and memory spaces divided into equal sized pages. The pages can easily be slotted in and out of the RAM due to the equal sized pages
What is Segmentation?	Processes are divided logically decides if the content of the segment works when segmented Processes are in different sizes Segments may be harder to fit into gaps due to the different sizes
What is Virtual Memory?	Used when RAM is full Instructions which are not being used are moved to spare space in the hard disk then swapped back in when they are needed
What are the negatives of Virtual Memory?	It may take more time to move instructions than executing them. Causes disk thrashing which can slow down performance. CPU can only execute instructions in the RAM.
How does an interrupt work?	Device sends a signal if it deemed important The fetch, decode, execute cycle checks if there is any interrupts If there is, the CPU has to stop what it is doing and carry that out instead
How do Stacks work with Interrupt?	Processes are stored on a stack. Interrupts are popped into the stack and are executed before any other processes can start. Interrupts with higher priority can interrupt another interrupt
What types of Interrupt are there?	Hardware interrupts Software interrupts Input/Output interrupts
What does Scheduling do?	Manages process that need to be executed. Each process is given a slice of time which it can execute for. Processes are stored in a queue. Processes can be blocked if needed later. Gives the illusion of multiple processes are running at the same time.
Give 4 Algorithms used to manage process queues	First Come First Serve Shortest Job First Round Robin Shortest Remaining Time
What can block a process?	Processes are blocked if they need a input or output request
Why is there Multilevel feedback queues?	They may have different priorities and algorithms Algorithms can move processes from queue to queue as needed
Name the 5 types Of Operating System	Multi-tasking operating systems Multi-user operating systems Distributed computer operating systems Embedded operating system Real-Time operating system
What does Multi-tasking operating systems do?	When one processor can run other processes nearly at the same time Allows for multiple applications to be running at once
What does Multi-user operating systems do?	There may be many different users on one computer Designed for the sharing of resources like files and programs
What does Distributed computer operating system do?	Operating system coordinates computer across network like they were a single system Used for factories or other industries
What is a Embedded operating system?	Highly specialised for a specfic purpose Small computer designed to fit into a machine or appliance Washing machine
What does Real-Time operating system do?	Ina safety critical environment used when processes need to be executed within a time frame Lots of redundancy in the system as it needs to be when there's an emergency
What is the BIOS?	BIOS stands for Basic Input Output System. Used in the ROM. Fast to read and is non volatile. Carries out instructions used to start the computer when it turns on.
What is the CMOS?	CMOS stands for Complementary Metal-Oxide Semiconductor Stores the BIOS
What is POST?	POST stands for Power On Self Test. When the computer is turned on the BIOS starts a POST. It then uses this data to start the computer or show a warning message. Prevents the BIOS from crashing in case of missing hardware.
What does the Kernel do?	The Kernel manages the operations of the computer and the hardware such as memory and CPU time.
What is the Bootstrap?	A program that runs after the POST. Loads the Kernel into the memory and hands over the computer. The Kernel then loads the all the needed programs into the memory.
Explain what the Dual BIOS?	Most modern computers have two BIOS's A main one which carries out the main processes A second one which restores the main BIOS if it fails
What does a Virtual Machine Do?	A digital program which acts the same functionally as a physical device Programs that run on virtual machine do know do not know they are on one
What is a Emulator?	A program which acts like the native console of a video game, allowing it to be run on other computers Allows PC's to run games which may be designed to run on a console
What do Virtual Servers do?	They have a small number of physical servers with a number of virtual servers on them. They operate the same as a physical server. Known as virtualisation.
What is Interpret Intermediate Code?	It complies its code into bytecode (intermediate code) which is easily translated by Java. It means that the bytecode language can be used for different devices. Only the virtual machine needs to be adapted for different devices .
What is a device driver?	Software that tells the Operating System how to communicate with another device.

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	Created by Lyle Winfield over 5 years ago