ITE 272 Final Exam Study Guide

vi command

Allows the user to edit a file.

vi filename

How do you open a file using vi?

:w

How do you save the file when using vi?

:q

How do you exit the file when using vi?

0

How do you navigate to the beginning using vi?

$

How do you navigate to the end using vi?

H

How do you navigate to the first line on the screen using vi?

M

How do you navigate to the middle line on the screen using vi?

L

How do you navigate to the last line on the screen using vi?

w

How do you navigate to the beginning of the next word using vi?

b

How do you navigate backwards to the beginning of the previous word using vi?

1G

How do you navigate to the first line of the file using vi?

G

How do you navigate to the last line of the file using vi?

I

How do you change to the mode where you can insert new lines?

esc

How do you exit out of the mode?

Root Account

The account that gives the user access to all the functions of the OS. The principal user account.

Man Pages

The online manual pages for UNIX/Linux commands and programs that can be accessed by entering man plus the name of the command or program.

Piping

A command that will list the outputs of one command to another. cat command is an example.

Chmod (owner, group, everyone) filename

How do you use Chmod?

0 = nothing, 1 = read, 2 = write, 4 = execute

What are the Chmod permissions?

useradd

What command adds a user?

userdel

What command deletes a user?

/etc/passwd

What command lists the user account information?

/etc/shadow

What command lists the user account passwords?

/etc/groups

What command lists the groups information?

ps

What linux process management command displays the current processes running?

top

What linux process management command displays the CPU processes?

kill

What linux process management command closes the processes?

ls

What command will list the information of the files?

cd

What command will change the directory of the files?

mkdir

What command will create a new directory?

pwd

What command will print the name of the current directory?

rm

What command will remove a file?

mv

What command will move a file?

cat

What command will concatenate a file or directory?

grep

What command will search for a pattern of a file or directory?

cp

What command will copy a file or directory?

General Purposes Processors

Used for data representing all kinds of users. It can be many kinds of inputs and outputs to design things for all kinds of users.

Special purpose Processors

Designed for a specific or limited function. Examples include embedded systems such as appliances (like microwave ovens) automobiles and peripherals (like printers).

Systems Architecture

The structure, interaction, and technology of computer components.

CPU, Primary Storage, Secondary Storage, I/O units, System Bus

What are the Computer Hardware components?

CPU

A general-purpose processor that executes all instructions and controls all data movement in the computer system.

Primary Storage

High-speed storage in a computer system that holds currently running programs and data immediately needed by these programs.

Secondary Storage

System devices that provide large-capacity and long-term data storage.

I/O Unit

Devices that perform external communication functions.

System Bus

The internal communication channel connecting all hardware devices.

Compactness, Accuracy, Range, Eace of Manipulation, Standardization. CARES

What are the Goals of data representation?

Describes the number of bits used to represent a numeric value. It has a limited range of values that can it represent.

Compactness/trade-off

The degree to which the result of a measurement conforms to the correct value. It can be achieved by balancing performance and cost.

Accuracy/trade-off

The range of numbers available to use uses more data slower. The more compact a device with a small arrange the more affordable it will be.

Range/trade-off

How easy it is for the computer to process the data. More complex devices require more time to perform functions.

Eace of Manipulation/trade-off

Ensures correct and efficient data transmission. The risk of losing functionality between devices.

Standardization/trade-off

Control unit, ALU, registers

CPU components

Control Unit

Responsible for moving data, accessing instructions, and controlling the arithmetic logic unit.

ALU

Contains circuitry for performing computation, comparison, and logic instructions.

Registers

Internal storage locations in a CPU. Each is capable of holding a single instruction or data item instruction and instruction sets

10111001

What is the Binary for the hexadecimal value for B9?

205

What is the decimal value of the unsigned binary number: 11001101

255

What is the decimal range for unsigned 8 bit binary numbers?

-80

What is the decimal value of the signed binary number: 10110000

A6

What would the decimal value for 166 be in hex?

106

What is the decimal value of the signed binary number: 01101010

10001011

The decimal number 139 is represented as a binary number:

211

The hexadecimal value for D3 is equal to the decimal value:

B9

11101001 in binary is written in hexadecimal as

Operating systems

A collection of utility programs for supporting users and application programs, allocating resources to multiple users and application programs, and controlling access to hardware.

Management of CPU, Memory, Processes, Secondary Storage I/O Devices, Users

What are the operating system management functions?

Perform basic tasks, prevent interference, provide a software platform

What are the responsibilities of operating system?

Kernel, service layer, command layer, application layer

What are the operating system layers?

Kernel

Manages resources and interacts with hardware.

Service Layer

Contains reusable components; acts as intermediary between programs.

Command Layer

The user interface.

Application Layer

Interconnection layer that includes communication protocols.

Multitasking Resource Allocation

The OS takes what it needs and everything else is available for the other process.

Meet each program's resource needs, prevent programs from interfering with one another, use hardware and other resources efficiently.

What are the Resource Allocation Goals?

Schedule resources based on allocation policies and meet current and anticipated needs, update records instantly.

What are the resource allocation functions?

Real Resources

A computer's physical devices and associated system software that physically exists.

Virtual Resources

Resources that are apparent to a user or program as being available but don't necessarily physically exist.

Process Management

Allow the OS to keep track of many different processes running at the same time.

Threads

A portion of process that can be scheduled and executed independently.

CPU Allocation

A thread controls a CPU for no more than a few milliseconds before it relinquishes control and the OS gives another thread a turn.

Ready State

Idled, pending availability of a CPU.

Running State

A thread retains control of a CPU until: the thread terminates or an interrupt occurs.

Blocked State

The state of an active thread that's been suspended by the OS and is waiting on the stack until interrupt processing has been completed.

Ready, Running, Blocked

What are the three Thread State?

Interrupt Processing

How the CPU handles interrupts and what happens to threads or processes that are being executed.

Preemptive Scheduling

A thread can be removed voluntarily from the running state.

Priority-Based Scheduling

Determines which ready thread should be dispatched to the CPU according to: first come first served, explicit authority, shortest time remaining.

Real-Time Scheduling

Guarantees a minimum amount of CPU time to a thread if the thread makes an explicit real-time scheduling request when its created.

Single-Tasking Memory Allocation

A memory allocation diagram, or memory map, shows physical memory as an array of addresses, with the lowest memory address at the bottom and the highest memory at the top.

Multitasking Memory Allocation

The OS finds free memory regions in which to load new processes and reclaims memory when processes terminate.

The Goals of Multitasking

Allow as many active processes as possible
respond quickly to changing memory demands of processes.
Prevent unauthorized changes to a process memory reign.
Perform memory allocation and addressing it as efficiently as possible.

Absolute Memory Addressing

Using memory address operands that refer to actual physical memory locations. This method requires process offsets.

Relative Memory Addressing

A method of computing physical memory addresses automatically. The CPU adds the process offset to all memory address operands before accessing memory.

Addressable Memory

The highest numbered storage byte that can be represented in a CPU or computer. Usually determined by the number of bits used to represent an address.

Contiguous Memory

The condition of all portions of a program or the OS being loaded into sequential physical locations in memory.

Noncontiguous Memory

Uses small fixed-size partitions.

Virtual Memory Management

Divides a program into partitions called pages.

Swap Space

A secondary storage region reserved for the task of holding pages not held in memory, its divided into page frames in the same manner as memory.

Page

A small fixed-size portion of a program, normally between 1 and 4 KB.

Page Hits

A reference to a page held in memory.

Page Fault

A reference to a page held in secondary storage.

Allow computer to make a service call to another computer for a particular service or file.

Purpose of Sockets

Pipes

A region of shared memory through which multiple processes executing on the same computer can exchange data.

Remote Procedure Calls

A protocol that enables a process on one computer to call a process on another computer.

File Control Layer

Provides service functions for manipulating files and folders.

Storage I/O Control Layer

Part of the kernel that accesses storage locations and manages data movement between storage devices and memory.

Command Layer

The operating system layer that serves as the user interface.

Logical Storage View

How the application and users see the file.

Physical Storage View

The physical way a file is stored in hardware.

Volumes

A container for a hierarchically organized set of folders and files.

File Association

A defined relationship between file types and the programs or OS utilities that manipulate them.

Hierarchical Directory Structure

Directories can contain other directories, but in a directory can't be contained in more than one parent.

Graph Directory Structure

Files and subdirectories can be contained within multiple directories.

Allocation Units

The minimum amount of space on a storage device that a file can occupy.

Advantage of Allocation Unit Size

Using a smaller unit size wastes less space when there is a lot of small files because less storage is allocated to one file.

Disadvantages of Allocation Unit Size

Can make processes significantly slower

Storage Allocation Table

Records which allocation units are free and which belong to files or folders.

Deletion

File is marked as deleted but the data is left in storage.

Undeleted

By reconstructing directory and storage allocation table contents.

Read, Write, Execute

What are the access controls for Unix/Linux?

Full

Copies all selected files and directories and clears archive attributes.

Differential

Copies only files and directories created or changed since the last normal or incremented backup.

Incremental

Copies only files and directories created or change since the last incremented backup.

File Migration

Balances each file versions storage cost with anticipated user demand for this version.

Fault Tolerance

Securing file content against hardware failure.

Mirroring

All disk write operations are made concurrently to two different storage devices.

RAID

Improves performance and fault tolerance.