1. Reference Text : Computer Fundamentals by Anita Goel
Module 1
Reference Text : Computer Fundamentals by
Anita Goel

2. Syllabus
Introduction to digital computer – Von Newman concept – A simple model of computer with acquisition of data, storage of data, processing of data, output of processed data. Details of functional units of a computer. Storage – primary storage and secondary storage.
Introduction to programming languages: types of programming languages - high level language , assembly language and machine language System software - Operating systems – objectives of operating systems, compiler, assembler and interpreter.

3. Computer 2 Types Digital Computers : Analog Computers :
uses distinct value to represent data internally.
Informations are represented using 0 and 1
Analog Computers :
represents data as variables
used to process analog data.
Analog data is of continuous nature and which is not discrete or separate.
temperature, pressure, speed weight, voltage, depth etc.

4. Digital Computers Von Neumann Concept
  a computer architecture
in 1945 by the mathematician and physicist John von Neumann
electronic digital computer with parts consisting of
processing unit containing an arithmetic logic unit and processor registers
a control unit 
a memory to store both data and instructions,
external mass storage
 input and output units.
 stored-program computer 
Bottleneck : - an instruction fetch and a data operation cannot occur at the same time because they share a common bus.

6. Central Processing Unit
Brain of the computer
Consists of ALU , Control Unit (CU) , registers and instructions
Executes stored program program instruction
Data and instructions are stored in memory before execution
CPU gets data and instruction from memory, interprets the program instructions and perform the required arithmetic and logic operations

7. Control Unit Arithmetic Logic Unit
Central Processing Unit
Control Unit Arithmetic Logic Unit
Registers

8. Arithmetic Logic Unit Consists 2 units Arithmetic unit Logic unit
Performs arithmetic operations on data
Ex: addition,subtraction ,multiplication etc
Performs logic operations on data
Ex: comparison of numbers,letters and special characters.
Uses registers to to hold data that is being processes.

9. Registers High speed storage area within CPU Least storage capacity
Directly accessed by CPU
Refers as CPU’s working memory
Used to store data,instructions,addresses and intermediate results.

10. PC IR
MAR
ACC
MBR DR

11. Important registers are
Accumulator ACC : Stores results of arithmetic and logic operations
Instruction register IR : contains current instruction most recently fetched
Program Counter PC : contains the address of the next instruction is to be fetched
Memory Address Register MAR : address of next location in the memory to be accessed
Memory Buffer Register MBR: temporary stores data from memory or data to be sent to memory
Data Register DR : stores the operands and any other data.

12. Word size : - size of register, indicates the amount of data with which computer can work at any given time.
May be in 8,16,32,64 bits

13. Control Unit Organizing the processing of data and instructions
Act as a supervisor, controls and coordinates the activities of other units of computer.
Directs the computer to carry out stored program instruction by communicating with ALU and the registers.
Uses IR to decide which circuit to be activated.
Instructs the ALU to perform the operation
CU tells when to fetch the data and instruction,what to do and where to store the program

14. Memory Unit Consists of Cache memory Primary memory Secondary memory
RAM
ROM
Secondary memory

15. Cache Memory
It is a storage buffer that stores the data that is used more often, temporarily and makes them available to CPU at fast rate.
Very high speed memory placed between RAM and CPU
Increases the speed of processing.
During processing ,CPU first checks cache for data,if not then CPU looks in the RAM for data.
No system bus for accessing the cache.

16. CPU has built in Level1 (L1) cache and Level2(L2) cache.
L3 Cache – cache on the motherboard.
Intel core i7
L KB
L2-6MB
L3-12MB
Very expensive
Small in size

18. Primary Memory Main memory of computer
Used to store data and instructions
Semiconductor memory
Provides a limited storage capacity – high cost
2 kinds
RAM
ROM
Non volatile memory
Permanent
Store std processing programs
Programmed by manufacturer

19. Interaction of CPU with memory

20. Secondary Memory Stores data and instructions permanently
Non volatile memory
Provides back up storage
High storage capacity
Cheaper
Takes longer time to access the data and instructions .
Hard disk, CD, Floppy disk.

21. Instruction Format
Describes the steps to be performed for carrying out a computational task.
A computer program is a set of instruction
Fields – instruction is divided into groups
The common fields are
Operation code – action that the processor must execute
Opcode-parameters of the action(location or operands)

22. Instruction format
Example : ADD command

23. INSTRUCTION SET Set of instructions that the processor understands
Set of all basic operations that a processor can accomplish.
Language that the processor understand
EX :
ADD A,B
MOV B,A
RAR

24. INSTRUCTION CYCLE
The series of steps for executing an instruction by CPU.
4 steps
Fetching
Decoding
Executing
Storing

26. 4 type of instructions
Memory access or transfer of data between registers
Mov B,A
Arithmetic instructions
Add B
Logic instructions
AND,OR
Control and conditional instructions
JMP,JC

28. BUS
Set of electronic signal pathways that allows information to travel between components inside or outside of a computer.
2 types
Internal (System Bus)
External Bus(Expansion bus)

29. External Bus
Connects different external devices , peripheral , expansion slots and I/O ports to the rest of computers
Allows expansion of computer’s capability
Slower than internal bus(System Bus)
Also referred as expansion bus

30. 3 kinds Data bus – used to transfer data between I/O devices and CPU
EISA
PCI
AGP
USB
Address Bus – Carries the address of different I/O device to be accessed
Control Bus – used to carry read/write commands,status of I/O devices etc.

31. Microprocessor
an integrated circuit that contains all the functions of a central processing unit of a computer.
Classified into two
RISC – Reduced Instruction Set Computer
CISC – Complex Instruction set Computer

33. CISC
has a large instruction set that includes simple and fast instructions for performing basic tasks, as well as complex instructions that correspond to statements in the high level language.
An increased number o f instructions (200 to 300) results in a much more complex processor, requiring millions o f transistors.
Instructions are o f variable lengths, using 8, 16 or 32 bits for storage.
AMD based on CISC.

34. RISC RISC has fewer instructions and requires fewer transistors
manufacturing cost of processor is less
The instruction size is fixed (32 bits).
speeds up the program execution when compared to CISC processors.
RISC processors can handle multiple instructions simultaneously by processing them in parallel.
Apple Mac G3 and PowerPC are based on RISC.

35. Athalon XP and P IV - Hybrid

36. Memory
Storage area used to store data,instructions and intermediate results.
Binary digits or bits – unit of memory
0 or 1 - one bit
Byte - group of 8 bits
Word – a group of bytes (2,4,or 8 bytes)

37. Memory Hierarchy Characterized on the basis of
Capacity – the amount of information that the memory can store
Access time – time interval between read/write request and the availability of data
Memory with fastest speed and largest capacity

39. Catagories Internal External Used by CPU to perform task Ex..
Used to store the large amount of data and the software
Also known as secondary memory

40. Internal Memory -Features
Limited storage capacity
Temporary storage
Fast access
High cost
Registers, primary memory and cache memory

41. External Memory Very high storage capacity Permanent storage
Slower access
Stores data and instructions that are not currently accessed by CPU
Cheapest

42. Memory organization With respect to CPU
Registers are placed inside the CPU
Cache memory is placed next in the hierarchy
Primary memory is placed next in the lab
Secondary memory is the farthest from CPU

43. Primary Memory
RAM
DRAM
SRAM
ROM
PROM
EPROM
EEPROM

44. RAM Random Access memory
Used to store data & instructions during the operation of computer
CPU interacts with RAM for processing
Volatile memory
Provides random access to the stored data
Read from and written to with the same speed
Size is small
Cost is high

45. 2 kinds
DRAM
SRAM

46. DRAM Dynamic RAM Common type of memory Used as main memory
Small and cheap
Uses transistors and capacitors
Memory cell – pair of transistor and capacitor
Transistor act as switch
Capacitor holds information as bits
Memory controller is used – refreshment of storage
Access speed -50 to 150 ns

47. SRAM Static RAM Used as cache memory High speed
Uses multiple transisitors(4 to 6) for each memory cell
Doesn’t have capacitor in each cell
No constant refreshing
More expensive
Stores information as long as it is supplied with power
Easy to use and very fast
Access speed – 2-10 ns

48. Memory Module PCB – Printed Circuit Board SIMM – DIMM
chip on one side of the PCB
Can store 8 to 32 bit simultaneously
DIMM
Memory chip on both side of the PCB
64 bit
SODIMM for portable computers-32 bit

49. ROM Non volatile primary memory
Does not lose its content when the power is switched off.
Has only read capability and no write capabilty
Programmed by manufacturer
stores BIOS

50. BIOS information required to boot system Permanent part of computer
Provides the resources available in the system
BIOD does
POST - program that runs automatically when system is booted and checks that the major hardware components are work properly
BIOS setup Program – built in utility ,lets the user to set many functions to control how the computer works.
Also initialize registers and loads device drivers
Bootstrap Loader

51. Bootstrap Loader
It is program to start the computer software for operation when the power is turned on.
Loads the OS into RAM and launches it
Resides in the ROM

52. 3 types of ROM
PROM
EPROM
EEPROM

53. PROM Programmed with special tools Contents cannot be changed
Thousands of diodes

54. EPROM Programmed by special tools
Can be erased by exposing it to UV light and reprogrammed
Have to be removed from computer for rewriting

55. EEPROM Can be erased by electric charges and reprogrammed
Do not have to removed from computer for rewriting

56. Flash Memory Special type of EEPROM Combines features of RAM and ROM
Random access memory
Data is not lost
High speed memory,durable and low energy consumption
Used in mobile phones,camera,laptop etc

58. Secondary Memory Magnetic tape drives Magnetic Disk Optical Disk
Floppy
Hard disk
Zip Disk
Optical Disk
CD ROM
DVD ROM
Recordable optical disk
Magneto optical disk

59. Access types Sequential Direct Access Magnetic tapes Magnetic disk
Optical Disk
Magneto –optical disk

60. Magnetic tapes It is a plastic tape with magnetic coating Cheaper
Durable , written , erased and rewritten
Sequential Access
Not suitable for data files that need to be updated often
Used to store data that are not frequently used

61. Features Inexpensive Store large amount of data Easy to carry
Not suitable foe random access
Slow access device
Need dust prevention, as dust can harm the tape
A 10 inch diameter reel of tape can store upto 180 million characters.

62. Working
Tape is divided horizontally into tracks and vertically into frames
Frame stores 1 byte of data and tracks in a frame stores 1 bit.
Data are stored in successive frames as a string with one data per frame.
Data is recorded on tape in the form of blocks
Record – group of data(block)
Each block read continually

63. Tape is mounted on magnetic tape drive for access. Drive mechanism
IRG – inter record gap
Provides time for the tape to be stopped and started between records
Tape is mounted on magnetic tape drive for access.
Drive mechanism
Consisit of supply reel, take-up reel and read/write head
The tape is moves on the drive from supply reel to take-up reel, with its magnetic coated side passing over the read/write head.

65. How do you read data from it?
The purpose of any magnetic tape unit is to write data on and read data from the tape used by the device. Tape is moved from a supply reel or hub to a take-up reel or hub on the magnetic tape transport section of the unit The magnetic oxide coated side of the tape passes in close proximity of  a read/write

66. Magnetic Disk
It is a thin plastic or metallic circular plate coated with magnetic oxide
Presence of magnetic tape – bit 1
Absence - bit 0

67. Features Cheap Can store a large amount o f data
Easy to carry or transport
Suitable for frequently read/write data
Fast access device
More reliable storage device
To be prevented from dust, as the read/write head flies over the disk.

68. Working
Tracks – the surface of disk is divided into concentric circles
The outermost track is numbered 0 and innermost track is the last one
Sector –division of tracks,it is a pie slice that cuts across all tracks
The data on disk is stored in sector

70. Magnetic disk is inserted into a magnetic disk drive for access
Magnetic disk is inserted into a magnetic disk drive for access. The drive consists of a read/write head that is attached to a disk arm, which moves the head. The disk arm can move inward and outward on the disk.
Storage capacity is measured in gigabytes(GB)
Double sided disk –tracks and sectors on both sides
Cylinder – set of same tracks on all disk.

71. Accessing data on the disk requires the following
The time taken to move the read/write head to the desired track is called the seek time.
• Once the read/write head is at the right track, then the head waits for right sector to come under it (disk is moving at high speed).
The time taken for desired sector o f the track to come under read/write head is called the latency time.
Once the read/write head is positioned at the right track and sector, the data has to be written to disk or read from disk. The rate at which data is written to disk or read from disk is called data transfer rate.
The sum o f seek time, latency time and time for data transfer is the access time o f the disk.

72. Floppy Disk
is a flat, round, single disk made o f Mylar plastic and enclosed in square plastic jacket
Floppy Disk Drive (FDD) is the disk drive for floppy disk
write-protcct slide tab that prevents a user from writing to it.

73. may be single-sided or double-sided disk
Portable
small and inexpensive
slower to access than hard disk
less storage capacity and are less expensive than hard disk.

75. Hard Disk
consists o f one or more platters divided into concentric tracks and sectors
mounted on a central spindle, like a stack.
can be read by a read/write head
The data is stored on the platters covered with magnetic coating.

77. Hard disk is a fixed disk. The disk is not removable from the drive
The hard disk and Hard Disk Drive (HDD) is a single unit.
The data can store on both sides o f each platter
the read/write head o f hard disk does not touch the disk during accessing.
can store up to 500 GB o f data

78. Zip Disk high-capacity removable disk and drive.
have the speed and capacity o f hard disk and portability o f floppy disk.
Zip disk are o f the same size as floppy disk
comes as a complete unit—disk, drive, connection cable, power cord and operating system.
It can be connected to the computer system externally using a parallel chord or SCSI cable.
capacity ranges from 100 MB to 750 MB.
used to store large files, audio and video data.

80. Optical Disk Flat and circular disc
Coated with reflective plastic material
Can be altered by laser lights
Can store large amount of data in a small space
Access time : 100 ns to 200ns
2 catagories
Read only
Recordable

81. Sectors and track in magnetic disk and optical disk

82. CD ROM Medium for storing music Can only be read and not written to
Cost is low
Access time is less
Data are stored as pits and lands on disk.
When laser light is focused on the disk, the pits scatter the light and the lands reflect the light to a sensor.

83. DVD ROM Digital Video Disk Read only memory
Store digital video or computer data
Improves on CD technology
Uses both sides of disk

84. Recordable optical Disk
CD-R – write once read many
CD-RW
data can be written, erased and re written
DVD-R
Allows recording of data

85. Magneto optical device
Use laser beams to read and magnetic field to write data to disk
data can be written, erased and re written
Expensive
Outdated

87. I/O Ports The external interface used to connect i/o devices
The different port are
Parallel port
Serial port
USB port
Firewire

88. Parallel Port An interface for connecting 8 or more data wires
Transmits 8 bits of data parallel.
Provides high speed data transmission
Eg: Used to connect printers

89. Serial Port Transmits 1 bit of data through a single wire
Slow speed data transmission
Used to connect modem , barcode reader etc.

90. USB Port
Allows different devices to be connected to computers without requiring rebooting
Plug and play

91. Firewire
Used to connect audio and video multimedia device like video camera
Expensive
Used for large data movement
Connect HDD and DVD drive

92. MIDI
Musical Instrument Digital Interface

93. Operating System
software that controls and coordinates the use of hardware among different sofs and users.
Intermediate between the user and computer hardware

94. Objectives To make the computer system convenient and easy to use
To use the computer hardware in an efficient way by handling the details of the operations of the hardware.

95. Functions of OS Process management Memory management File management
Device management
Protection Security
User interface

96. Process management Control access to shared resources
Control the execution of program
Create, execute and delete a process
Cancel or resume a process
Synchronization and communication of processes

97. Memory Management Allocate memory Free memory Re allocate memory
Keep a track of memory usage

98. File management Create and delete both files and directorirs
Provide access to files
Allocate space for files
Keep backup of files
Secure files

99. Device Management Open, close and write device drivers
Communicate, control and monitor the device driver

100. Protection Security Protects the resources of system
Provides security mechanisms
Prevents unauthorized access to computer

101. User interface
Provides an Interface between the user and computer hardware
Interface is a set of commands which the user interacts with the application and the hardware.