Operating Systems

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Explain Windows Vista

2006, more built in security and requires less rebooting 33% faster than XP/200 More reliable UAP - user account protection

Explain Basic Input/Output System (BIOS)

A low level program code that: initiates hardware devices, performs POST, runs a startup prg inside BIOS Initializes the screen and keyboard, tests hardware, initializes the drives, loads the main OS, typically stored in NVRAM

Describe processes

A process is an instance of an executing program Processes are the entities among which the kernel must share the various resources For limited resources the kernel initially allocates an amount of the resource to the process and adjusts as needed On process termination all resources are releases for reuse by other processes Uses fork system call to create child process Duplicate of parent proc Inherits data, tack and heap segments Each process has a unique PID

Explain Windows Server 2008

AD - read only domain controller implemented so hackers cannot make changes at remote locations to be replicated to the main DC Failover clustering - cluster validation Hyper-V - allows multiple independent OS at the same time

Describe the history of Unix/linux

AT&T developed unx but never licensed the kernel 1973 kernel rewritten in C, license to some universities 1991 Linux created free self contained, run on PCS or other HW Unix was first true multi-tasking/multi user OS They use different shells Some use a GUI

Explain File Systems

All information stored on a computers hard disk is managed through a file system File system allocates locations for storage records where specific information is kept Overall purpose of FS is to create a structure for filing data

Dual Mode Operation

Allows OS to protect itself and other system components Kernel mode and user mode HW instructions allow switching from one mode to the other Certain operations can be performed only while the processor is operating in kernel mode

Describe Dual Mode Operation

Allows OS to protect itself and other system components User mode and kernel mode Hardware instructions allow switching from one mode to another Certain ops can be performed only while the processor is operating in kernel mode

Role of Application software

Any program a user might choose to run in a computer, word processors, databases. The OS manages the communication among the applications the user and the computer

Describe the Role of Application Software

Any program a user might choose to run on a computer (word, DB, spreadsheet, an OS manages the comm along applications, the user and the computer

BIOS

Basic Input/Output System P-R-L-I-T Low level program code Perform POST Run startup program inside the BIOS Initiates HW devices Loads the main operating system Initiates screen, keyboard, test HW, initializes the drives Typically stored in Non-Volatile Random Access Memory (NVRAM)

Describe Time Sharing Systems

Central computer system that is used by multiple users and applications simultaneously - used to perform massive calculations

Explain the Kernel

Consists of essential program code of the operating system Manages and allocates computer resources Jobs include, managing interactions with the CPU, memory mgmt., process scheduling, creation termination

Kernel

Consists of the essential program code of the operating system Manages and allocates computer resources. Kernel code executes in kernel mode (supervisory mode) with full access to all physical resources of the computer. In user mode the CPU can access only memory that is marked as being in user space

Summarize the Windows Registry

Database called a hive Separate hives for system information, default user prefernces, software installation and security System hive is required to boot the system Eerytime the sys successfully boots the system hive is saved as last known good Installed software changes hives System restore periodically saves hives

Explain windows XP design

Desktop version with core elements of windows 2K More capabilities for multimedia apps Better security with firewall Remote desktop Home, pro, tablet, media, XP-64 bit 32 bit multitasking OS Extensible - layered architecture Portability - movable from one hw architecture to anoterh with few changes HAL makes it portable Reliable (virtual memory) Compatible - IEEE 1003.1 Performance - can comm with high speed message passing International support - NLS (national language support)

Explain Multitasking

Earlier versions of OS allowed prgms to directly access hardware Prone to hangs, instability Todays OS manage access to hardware to facilitate multi-tasking Cooperative multi-tasking - OS gives control to prgm waits for it to be returned Preemptive multitasking - OS is in control at all times

Explain Windows 7

Enhanced version of windows 7 Uses less memory and run background services only when needed MS security essentials - real time protection includes AV Run apps in XP mode Comes in 32/64 bit version

Explain users and groups

Every user has a unique username and a numeric user ID (UID) Defined by a line in the system password file, etc/passed Organize users into groups to control access to files and other resources Users can belong multiple groups Each group is identified by a single line in the system group file /etc/group UID 0 is root

Summarize Windows Server 2003

Faster net login authentication New tools for managing server resources Ability to run 64-bit itanium processors Remote server management through RDP

Describe Mac Operating Systems

GUI first to hit the market, OS-X built on Darwin unix P2p networking standard on mac os Local talk networking with every printer port Always for desktop Known for graphics support 10.3 safari 10.4 works with intel processors 10.5 time machine 10.6 no longer supports apple talk only uses TCP/IP only works on intel 7 works with I cloud

Explain Cache

Internal clock of CPU is faster than external Level 1 runs at same speed as the processor Level 2/3 runs at same speed as the external CPU cache

Define Operating System

Is a set of basic programming instructions to computer hardware, forming a layer of programming code on which most other functions of the computer are built

Summarize the purpose of operating systems:

Is a set of basic programming instructions to computer hardware, forming a layer of programming code on which most other functions of the computer are built User view - OS provide an environment in which a user can execute programs, ease of use, performance a concern resource utilization is not Basic task of OS is IO functions

Explain the shell

Is a special purpose program designed to read commands typed by a user and execute apt programs in response CLI command line interpreter interface Bourne C Korn Bourne again Shell (BASH) most widely used on linux

Explain linux input and output

Linux splits all devices into three classes Block devices Character devices Network devices

Identify Early Microsoft Operating Systems

MS-DOS and PC -DOS Windows 3.x First popular version of windows using GUI Windows 95 MS first true 32 bit OS Eliminated 640 KB memory limit Introduced "desktop" Introduced PnP Introduced Registry IE integrated Windows 98/ME Expanded 95 Developed for home users Windows NT - OS kernel ran privileged mode C2 TS rating from gov't Win 2K - built on NT (supported VPNs, AD, Kerberos, intellimorror)

Kernel Mode

Mode bit-0

User Mode

Mode bit-1

Explain Linux File Systems

Modeled after UFS EXT2 - reliable file system with large disk storage EXT3 - added journaling EXT4 - supports file sizes up to 16 TB Laid out in logical blocks - blocks, sectors and cyl groups Mounts FS as a sub-FS of root All FS are referred to by path name Linux Proc file system - does not store data, proc must implement a directory structure Stores info in memory until it has time to write to the disk Graceful shutdown needed

OS must support

Multitasking, High-speed network applications, more powerful I/O capabilities. Must have Time sharing, Real-Time, Multiuser, Multitasking

Explain file system functions

Partition and format disks Organize files using directories and folders Establish file naming conventions Provide utilities to maintain and manage the FS and storage media Provide for file and data integrity Enable error recovery or prevention Secure info on files

Explain Input and Output devices and device drivers

Primary function of any OS is to provide basic IO support for app s/w Translate reqs from sw to hw, thru dev drivers and through controller and adapter boards for hardware Adapters are between hw components OS doesn't support specific features of each device Device driver advantages - only essential code is necessary to build into the OS kernel, use of devices not linked to OS, the # of IO devices an expand Use manufacturers drivers Procedures to install vary - tared or zipped In unix and linux the kernel contains most drivers - loadable modules

Jobs performed by Kernel

Process Scheduling Provision of system call APIs Managing interactions with the CPU Memory management Managing I/O device and networking activities

Explain System Calls

Programming interface to the services provided by the OS Typically written in a high level language Mostly accessed by programs via a API rather than direct system call

Explain the application programming interface (API)

Software designed to communicate with the application and the end user defines a set of functions that are available to the app programmer translates requests from an app into code that an OS kernel can understand and pass on to HW

Multi-User System

Supports multiple users who are accessing the computer's operating system hardware and software facilities. Both time-sharing and real-time systems can be multiuser systems.

Describe Multiuser systems

Supports multiple users who are accessing the computers and operating systems hardware and software facilities Client/user systems- a small part of the work is done on a central computer server,

Explain CPUs

System architecture built around the CPU, buses Core - does the reading and execution instructions Multi-processor computers have multiple physical CPU chips CISC only needs general purpose HW/RISC more complex more expensive

Describe file system mounting

The mount point is the location within the file structure where the file system is to be attached On *nix as /filename Microsoft uses drive letters

Explain how system calls are used

Three most common APIs are Win32, POSIX and JAVA for VMs.

Explain UNIX file systems

UFS - hierarchical file system, expandable, supports large storage, excellent security and reliable

Real-Time Systems

Used when rigid (well defined, fixed) time requirements must be met. Often used as a control device in a dedicated application. Functions correctly only if it returns the correct result within time constraints. ex car engines, manufacturing tools.

Describe Realtime Systems

Used when rigid time reqs must be met, often used as a control device in a dedicated app, functions correctly only if it returns the correct result within the time constraints Some are general purpose computers (ex unix with special apps)

Explain Windows File Systems

Windows XP, 7, Server 2003, and Server 2008 support EFAT16 FAT32 NTFS FS for DVD/CD ROMS and USBs EFAT16 - DOS - maximum volume sixe 4 GB/max file size is 2 GB FAT32 - windows 95 release 2 FAT64 is for larger volumes/files NTFS - Started with NT, uses Master File Table (appx 1 MB) security, ownership, and permissions meets US gov't security standards Journaling to keep log Hot fix capabilities CDFS/UDF - CD/DVD file systems

BIOS

a low level program code that performs P-R-I-L-I-T Performs Power On Self Test (POST) Runs a startup program inside the BIOS Initiate hardware devices Loads the main operating system Initiates the screen and keyboard, tests hardware, initializes the drives Typically store in Nonvolatile Random Access Memory (NVRAM)

Data Bus

allows components to share info # of bits in the bus indicates how many bits of data can be transferred from memory to the CPU

Time Sharing System

central computer system that is used by multi-users and applications simultaneously. Used to perform massive calculations or manipulate huge amounts of data. Example is a mainframe.

Control Bus

information to keep the CPU informed about the status of resources and devices connected to the computer Memory read and write status, interrupt requests

Address Bus

internal communications pathway specifies source and target addresses for memory read and writes at external clock CPU Width of address is the # of bits that can be used to address memory 32 bit address bus 4 GB mem addresses 64 bit address bus - 16 TB memory addresses Date Bus - allows components to share info # of bits in the bus indicates how many bits of data can be transferred from memory to the CPU Control Bus - information to keep the CPU informed about the status of resources and devices connected to the computer Memory read and write status, interrupt requests