ITP125: Chapter 2 - Operating Systems

Windows 95/98/ME

-network & internet functionality = afterthought

-no security was inherent

-could bypass login screen by hitting cancel

Windows NT

has networking built into OS but security still issue

Windows 2000/2k

1st Windows built with security mindset; still had issues with usability over secuirty

Windows XP SP0

first firewall but it was disabled and hard to find

Windows XP SP2

enabled firewall by default and made it more obvious to the user

Windows Vista

designed entirely from security standpoint; buggy & slow

-kept asking users "Do you really want to do this? Users eventually stopped taking alerts seriously

-secuirty > usability

Windows 7

solved may of bugs in Vista and made secuirty architecture less annoying

-good balance btwn security & usability

Linux

-open source OS
-used to be for hackets but in more recent times, new distributions = becoming more user friendly to install and use

Boot Processes: POST

Power-On Self Test
-process performed by firmware immediately after a computer or other electronic devices is powered on

What is POST part of?

pre-boot sequence and ONLY once it is complete does the system load the OS

POST Functions

-verifies integrity of BIOS, system memory and size, & CPU
-discovers, initializes, and catalogs all syste, buses w/ devices
-identifies, organizes, and selects which devices are available for bootin

Boot Processes: BIOS

Basic Input/Output System
-type of firmware used during the booting (POST) process

-specifically designed to work w/ particular motherboard model

BIOS function

fundamental prupose is to initialize and text system hardware (POST) and load an operating system from a boot device
-not in macs

Boot Processes: UEFI

Unified Extensible Firmware Interface
-specification that defines a software interface btwn firmware and OS

How are BIOS and UEFI different?

UEFI replaces BIOS in most hardware released since 2014 & is also used in macs

-better than BIOS bc can boot from disks larger than 2 TB, has CPU find. drivers, and ability to support network capabilities even in pre-boot

motherboard

main (printed circuit) board that allows communications btwn many of the components of the system such as CPU and memory and provides connectors for other peripherals

Central Processing Unit (CPU) [microprocessors]

chip within computer tha carries out instructions of a computer program by performing basic arithmetic, logica, control and input/output operations specified

-some computers have multi-core processors (single chip containing 2 or more CPUs called cores)

RAM (random access memory)

-volatile storage: stored info = lost if device is powered off
-allows data to be accessed in same amt of time irrespective of the physical location of the data in memory
-fast, temporary storage used by system to store info/processes currently in use

Hard Drive

data storage device used for storing/retrieving digital info & retains stored data even when powered off

SSDs (solid state drives)

flash memory equivalent to Hard drive but more expensive in price per unit of storage

-outperform hard drives in speed, power consumption, and sometimes durability

What is the purpose of an operation system

-software that interacts with and manipulates hardware so that users don't have to

-manages hardware and software resources

-establishes common API

API (application programming Interface)

-set of libraries for writing applications

-allows programs to be written for a common platform, and not for individual hardware

What is a program/application?

set of executable code

What is a process?

single instance of a computer program

-can have multiple (each window [not tab] you have open)
-task manager

What is a thread?

smallest unit of processing that can be scheduled

Interface

command line interface or graphical user interface (GUI)

kernel

-central manager of resources

-manages input/output requests from software and translates them to data processing instructions for CPU

How is information processed within a computer? Describe how the data moves through different storage locations

Hard Drive <--> RAM/Memory <--> CPU/Processor

upon request by user, Kernel handles & manages data being moved from slow hard drive into quicker RAM and briefly into and out of processor. Once process = complete, goes back.

What is paging/virtual memory?

allows for memory to be "swapped" out to the hard disk when there is not enough RAM to hold everything attempting to be stored

What are interrupts?

way for hardware or software to signal to processor that an event needs immediate attention

-processor responds by suspending its current activies, saving its state, and execuing interrupt handler to deal with event

What is the purpose of a file system?

provides mechanism for data managment on non-volatile storage such as hard drives, SSDs, and flash storage

-creates and manages files and directories