2. COMPUTER
Computer is an advanced electronic device that takes raw data as
input from the user and
processes it under the control of set of instructions (called
program), gives the result (output), and saves it for the future use.
A computer system is made up of both hardware and software.
Software is another term for computer program.
Software controls the computer and makes it do useful work.
Without software a computer is useless.
Hardware refers to the physical components that make up a
computer system.
These include the computer's processor, memory, monitor,
keyboard, mouse, disk drive, printer and so on.
3. FUNCTIONALITIES OF A COMPUTER
Any digital computer carries out five functions in gross
terms:
• Takes data as input.
• Stores the data/instructions in its memory and use them
when required.
• Processes the data and converts it into useful information.
• Generates the output
• Controls all the above four steps.
4. COMPUTER ADVANTAGES
1) High Speed
2)Accuracy
3)Storage Capability
4)Diligence
5)Versatility
6)Reliability
7)Automation
8)Reduction in Paper Work
7. TYPES OF COMPUTER
Computers can be broadly classified by their speed
and computing power.
1)PC (Personal Computer)
It is a single user computer system having moderately
powerful microprocessor
8. 2) WorkStation
It is also a single user computer system which is similar
to personal computer but have more powerful
microprocessor.
9. 3) Mini Computer
It is a multi-user computer system which is capable of
supporting hundreds of users simultaneously.
10. 4) Main Frame
It is a multi-user computer system which is capable of
supporting hundreds of users simultaneously.
Software technology is different from minicomputer.
11. 5) Supercomputer
It is an extremely fast computer which can execute
hundreds of millions of instructions per second.
12. Computer System Hardware
Hardware represents the physical and tangible components
of a computer i.e.
The components that can be seen and touched.
Examples of Hardware are following:
Input devices -- keyboard, mouse etc.
Output devises -- printer, monitor etc.
Secondary storage devices -- Hard disk, CD, DVD etc.
Internal components -- CPU, motherboard, RAM etc.
14. Relationship between Hardware and Software
• Hardware and software are mutually dependent on each other. Both of
them must
work together to make a computer produce a useful output.
• Software cannot be utilized without supporting hardware.
• Hardware without set of programs to operate upon cannot be utilized
and is useless.
• To get a particular job done on the computer, relevant software should
be loaded into
the hardware
• Hardware is a one-time expense.
• Software development is very expensive and is a continuing expense.
• Different software applications can be loaded on a hardware to run
different jobs.
• A software acts as an interface between the user and the hardware.
• If hardware is the 'heart' of a computer system, then software is its
'soul'. Both are
complimentary to each other.
15. Input/Output Devices:
Input Devices
Following are few of the important input devices which
are used in a computer:
Keyboard
Mouse
Joy Stick
Light pen
Track Ball
Scanner
Graphic Tablet
Microphone
Magnetic Ink Card Reader(MICR)
Optical Character Reader(OCR)
Bar Code Reader
Optical Mark Reader(OMR)
17. Output Devices
Following are few of the important output devices
which are used in a computer.
Monitors
Graphic Plotter
Printer
Speaker
20. Computer Memory Types
1. Primary memory (Main memory)
2. Secondary memory
3. Cache memory
Memory is used to store the information (programs and
data) that the computer is currently using. It is
sometimes called main or primary memory.
RAM - random access memory. This means that any
location in memory may be accessed in the same amount
of time as any other location. Memory access means one
of two things, either the CPU is reading from a memory
location or The CPU is writing to a memory location
RAM is a form of short term or volatile memory.
Information stored in short term storage is lost when the
computer is switched off.
21. RAM is of two types
• Static RAM (SRAM)
• Dynamic RAM (DRAM)
23. SRAM (pronounced ES-RAM)
Is made up of four to six transistors.
It keeps data in the memory as long as power is
supplied to the system unlike DRAM,
which has to be refreshed periodically. As such,
SRAM is faster but also more expensive,
Making DRAM the more prevalent memory in
computer systems.
SRAM uses more chips than DRAM for the same
amount of storage space, thus making the
manufacturing costs higher. So SRAM is used as
cache memory and has very fast access.
24. Common types of DRAM
Synchronous DRAM (SDRAM) “synchronizes” the memory
speed with CPU clock speed so that the memory controller
knows the exact clock cycle when the requested data will be
ready. This allows the CPU to perform more instructions at a
given time. Typical SDRAM transfers data at speeds up to
133 MHz.
Rambus DRAM (RDRAM) takes its name after the
company that made it, Rambus. It was popular in the early
2000s and was mainly used for video game devices and
graphics cards, with transfer speeds up to 1 GHz.
Double Data Rate SDRAM (DDR SDRAM) is a type of
synchronous memory that nearly doubles the bandwidth of a
single data rate (SDR) SDRAM running at the same clock
frequency by employing a method called "double pumping,"
which allows transfer of data on both the rising and falling
edges of the clock signal without any increase in clock
frequency.
25. DDR1 SDRAM has been succeeded by DDR2, DDR3, and most recently,
DDR4 SDRAM. Although operating on the same principles, the modules
are not backward-compatible. Each generation delivers higher transfer
rates and faster performance. The latest DDR4 modules, for example,
feature fast transfer rates at 2133/2400/2666and even 3200 MT/s.
26. Single In-Line Memory Module (SIMM)
SIMM modules were widely used from the late 1980s to
1990s, and are now obsolete. They typically had 32-bit
data bus and were available in two physical types—30-
and 72-pin.
Dual In-Line Memory Module (DIMM)
Current memory modules come in DIMMs. "Dual in-
line" refers to pins on both sides of the modules. A
DIMM originally had a 168-pin connector supporting
64-bit data bus, which is twice the data width of
SIMMs. The wider bus means that more data can pass
through a DIMM, translating to faster overall
performance. Latest DIMMs based on fourth-generation
double data rate (DDR4) SDRAM have 288-pin
connectors for increased data throughput.
27. Read Only Memory (ROM)
ROM stands for Read Only Memory. The memory from which we can
only read but cannot write on it.
This type of memory is non-volatile. The information is stored
permanently insuch memories during manufacture.
A ROM, stores such instructions that are required to start a computer.
This operation is referred to as bootstrap.
ROM chips are not only used in the computer but also in other
electronic items like washing machine and microwave
28. Types of ROM
1. MROM (Masked ROM)
2. PROM (Programmable Read only Memory)
3. EPROM(Erasable and Programmable Read Only Memory)
4. EEPROM(Electrically Erasable and Programmable Read
Only Memory)
Advantages of ROM
The advantages of ROM are as follows:
• Non-volatile in nature
• These cannot be accidentally changed
• Cheaper than RAMs
• Easy to test
• More reliable than RAMs
• These are static and do not require refreshing
• Its contents are always known and can be verified
