1. Unit-1, Chapter-1 Introducing Computer Systems

2. Topics The computer defined Computer for individuals
Computer for organizations
Parts of a computer
Information processing cycle
Essential computer hardware

3. The computer defined
An electronic device that process data and converts it into useful information.
Computers work based on the Programmed instructions.
Based on the way computers represent data, we have 2 categories of computers
Digital computers: they convert all the data into numbers and process it.

4. Analog computers: Represent data as variable points along a continuous spectrum of values.

5. Computers can be categorized in many ways:
No of people using them
Computer for individuals
Computer for organizations
Power
Capacity to perform different tasks

6. Computer for individuals
Computer meant to be used by a single person.
Six types of computers in this categories
Desktop computers
Workstations
Notebook computers
Tablet computers
Handheld computers
Smart phones

7. They are also called as Personal computers (PCs) as they are designed for use by a single person.
They are called as Microcomputers, because they are smallest computers for use.
PCs can be connected to different computers or to a network of computers.

8. Desktop Computers
A computer that is designed to sit on a desk or a table.
Used everywhere (Schools, offices, homes, etc.) and by everyone.
Todays Desktop computers are very powerful when compared to the ones a few years ago.

9. Tasks: Editing music, video and Photographs, Play games, Communicate etc.
The main component in a desktop computer is the system unit (consists of processing and storage devices)
2 Common designs
Horizontal oriented model
Vertical oriented tower model

11. Workstations
Workstation is a specialized single user computer that has more power and features than a standard desktop PC.
These are used by scientists, engineers and animators who need a system with above average speed and power to perform high end tasks.

12. They have high resolution monitors and accelerated graphics.
Suitable for advanced architectural or engineering designs, animation, editing etc.

13. Notebook Computers
Approximately the size of the notebook (8.5 x 11 inches).
Frequently used on the laps, hence they are called as Laptop Computers.
They operate on alternating current as well as on batteries.
They offer full functionality like desktop PC and can be taken anywhere.

14. Because of their portability, they fall under the category of mobile computers.
Docking Stations, which connects notebook to monitors, keyboards and other devices like desktop PC.

16. Tablet PCs
Portable, full featured computers.
Offer all the functionality of notebooks but are light weight and accept input from stylus or digital pen.
Support of foldout keyboard and option for connecting it to keyboard and monitors is available.

18. Handheld PCs
They are small enough to fit in hands.
The most popular type is personal digital assistant (PDA).
Size- like an appointment book. Used for saving contacts, keeping track of meetings.
Can exchange data with larger computers (wired or wireless connection)

19. Many offer other functionalities like music player, camera, GPS, etc.

20. Smart Phones
Phones offering advanced features not found in typical cellular phones are called as smart phones.
Access to web, includes special software (OS and application software) and hardware (Camera, finger print scanner).

22. Computers for Organizations
Computers that handle need of many people at a time.
Used in organizations like Business, IT Companies.
These computers support thousands of people to use computers at a time, sitting thousands of miles away.

23. Network Servers
Individual computers are connected through network to centralized computer(s) known as Network Server.
It has specialized software and hardware so that it can performs tasks of a primary computer in the network

24. Group of servers working together – Clusters or Server Farms.
Servers can be divided based on the tasks that they support. Print servers, Servers for communication, etc.
PC-based server are best suited because PCs are general purpose machines.
Connection could be wired (PC with Server) or wireless (Notepad with Server)

26. Each user accesses the mainframe through a device called as Terminal.
Mainframe Computers
Used in large organizations such as Insurance companies, banks, etc. where many people access same data.
Each user accesses the mainframe through a device called as Terminal.
2 types of Terminals
Dumb Terminal
Intelligent Terminal

27. Dumb Terminal does not process or store data, It is used only as an input/output device.
Intelligent Terminal can perform some processing, but it usually doesn’t have any storage.
A terminal could also be an desktop PC with all the basic functionality.
Mainframes are powerful and supports thousands of user at a given time.

28. Mainframes lack flexibility. They are task oriented computers
Mainframes lack flexibility. They are task oriented computers. (limited set of tasks)

29. Minicomputers
Released in 1960, minicomputers got their names when compared to the computers of that age.
Their capacity is somewhere between mainframes and personal computers.
Can serve hundreds of user at a time.

30. Supercomputers
These are the fastest computers ever made and their size is very large in size
They can process huge amount of data in small time.
They can perform 1 trillion calculations per second (thousands of processors)
They are used in fields where we require extreme calculating power and solve highly complex problems.

31. Used in Weather forecasting, modeling complex processes like nuclear fission, etc

32. Parts of a computer
Irrespective of the type of computer, a complete computer will have the following parts.
Hardware
Software
Data
User

33. Hardware
Mechanical devices that make up the computer are called as Hardware.
H/W is that part of the computer that we can touch.
Interconnected hardware devices are used for performing computer’s operations.
Sometimes, the term device is used instead of hardware.

35. Software
Software is a set of instructions that makes a computer perform tasks.
Programs refer to a piece of software.
Some programs exist primarily for the computers own use (to perform tasks and manage its own resources).
Other programs are also available which perform other specific tasks of the user.

37. Data
Data consists of individual facts or pieces of information.
Computer’s job is to process these data and convert them to useful information.
Example: Data stored in tables, information depicted as charts.

38. Users
People who operate computers are known as Users.
Computers involve human interaction at one or the other level.

39. The Information Processing Cycle
Computers accepts data, process it and converts in into useful information.
Numbers of operations are involved in this. These operations are part of the Information Processing Cycle (IPC).
Steps involved in IPC are receiving inputs, processing, displaying and storing results

40. The IPC has 4 parts, each parts involves 1 or more computer components.
Input: Computer accepts data from source (program or user) for processing
Processing: Based on instructions, the inputted data is processed.
Output: The computer may be required to display the results to the output device. (Printer, Monitor or even Speaker)
Storage: Computer can permanently store the results of processing on storage media.

42. Essential Computer Hardware
A Computer’s hardware falls into one of the four categories:
Processor
Memory
Input and Output
Storage

43. Processing Devices
Transforming raw data into useful information is called Processing, Components used are Processor and Memory.
Processor is the brain of the computer.
PCs use multiple microprocessors usually made up of silicon.
Microprocessor is placed into the computer’s motherboard.

44. Motherboard is a rigid rectangular card which connects the processor with all the computer’s hardware.
Dedicated circuit boards (Sound, Video, Network etc.) connect to the motherboard.
Central Processing Unit (CPU) refers to the computer’s processor.

46. Two most important type of memory are
Memory devices
Memory is one or set of chips that store data temporarily or permanently.
Two most important type of memory are
Random Access Memory (RAM)
Read Only Memory (ROM)

47. Random Access Memory (RAM)
RAM holds that data and instructions that are being used by the CPU.
When a program is run, it is loaded into the memory. All the data required by the program are also loaded into the RAM.
Data is both read and written into RAM, hence it is called read/write memory

48. RAM is volatile memory, it loses data when computer is shut off or when there is power failure.
RAM affects the performance of the computer. More the RAM, more is the data stored in RAM, more processing can be done.
Measurement units: Byte
Example: kilobyte(KB), megabyte(MB), gigabyte(GB) and terabyte(TB)

50. Read Only Memory (ROM)
ROM stores data permanently, non volatile.
It holds instructions that are required to operate the computer.
When computer is turned on, it checks ROM for start-up instructions and hardware information.

52. Input and Output Devices
Interaction between the user and the computer is enabled used input and output devices.
Input devices: Keyboard, Mouse, Trackball, Touchpad, Joystick, Scanner, Digital camera and Microphone.
Output devices: Monitor, Printer, Speaker.

53. Touch Screen acts as both input and output device.
Communication device such as modem acts as both input and output device.

55. Volatile and Non volatile
Storage Devices
Storage devices are used to hold the data permanently, even when the computer is not in use.
RAM and Storage devices- working
Differences:
Space or Capacity
Volatile and Non volatile
Speed and Cost

56. Magnetic Storage: A magnetic disk spins around its center
Magnetic Storage: A magnetic disk spins around its center. Read/write heads are used to read and write data.
The device that holds the disk is called as disk drive.
Non removable disks (hard disks) are used as primary storage device.

58. Optical Storage: Devices that use lasers to read and write data to the reflective surface of an optical disc.
CD-ROM most common type of optical disc with capacity of 700mb. Information once written can’t be changed.
DVD (Digital video disk) can store data from 4.7 gb to 17gb.