The document discusses hardware and software components of a basic desktop computer. It defines hardware as the physical parts of a computer like the keyboard, monitor, and processing unit. The most important hardware is the motherboard, which contains many parts that power and control the computer. Software consists of electronic instructions that tell the hardware how to perform tasks. There are two main types of software: system software that runs the computer hardware, and application software that allows users to accomplish tasks. Hardware and software work together, with software directing the hardware via instructions processed by the central processing unit.

1. Hardware
Hardware refers to the physical elements of a computer. This is also sometime called the
machinery or the equipment of the computer. Examples of hardware in a computer are the
keyboard, the monitor, the mouse and the processing unit.
However, most of a computer's hardware cannot be seen; in other words, it is not an external
element of the computer, but rather an internal one, surrounded by the computer's casing (tower).
A computer's hardware is comprised of many different parts, but perhaps the most important of
these is the motherboard. The motherboard is made up of even more parts that power and control
the computer.
In contrast to software, hardware is a physical entity. Hardware and software are interconnected,
without software, the hardware of a computer would have no function. However, without the
creation of hardware to perform tasks directed by software via the central processing unit,
software would be useless.
Software, commonly known as programs, consists of all the electronic instructions that tell the
hardware how to perform a task. These instructions come from a software developer in the form
that will be accepted by the platform (operating system + CPU) that they are based on. For
example, a program that is designed for the Windows operating system will only work for that
specific operating system. Compatibility of software will vary as the design of the software and
the operating system differ. Software that is designed for Windows XP may experience a
compatibility issue when running under Windows 2000 or NT.
Practical computer systems divide software systems into two major classes:
 System software: Helps run computer hardware and computer system itself. System
software includes operating systems, device drivers, diagnostic tools and more. System
software is almost always pre-installed on your computer.
 Application software: Allows users to accomplish one or more tasks. Includes word
processing, web browsing and almost any other task for which you might install software.
(Some application software is pre-installed on most computer systems.)
Software is generally created (written) in a high-level programming language, one that is (more
or less) readable by people. These high-level instructions are converted into "machine language"
instructions, represented in binary code, before the hardware can "run the code". When you
install software, it is generally already in this machine language, binary, form.

2. Basic Operations [src]
By Paul Mullins: constructed image
Desktop Compute
Original Basic_desktop_computer_
under CCA by user Vanes
Input
Whatever goes into the computer. Input can take a variety of forms, from commands you enter by
keyboard to data from another computer (via a network connection) or device
(via direct or network connection).
A device that feeds data into a computer, such as a keyboard or mouse, is called an input device.
Output
Any information (data) that comes out of a computer. Output devices can be other computers,
display screens, speakers, and printers.
Storage
Computer data storage is referred to as storage or memory, which can save digital data.
Examples are RAM, hard disks, CDs, DVDs and removable flash memory sticks.
Permanent, or non-volatile, storage devices do not require power to remember the data
stored. The mass storage devices shown above are non-volatile; a loss of power does
not affect their ability to retain data. This category also include ROM (Read Only
Memory).
Temporary or volatile storage is more often called "memory". A loss of power means
that any data stored will be lost irretrievably. When you are using an application, such
as a word processor, the data (the document you are working on) is stored in RAM
(Random Access Memory). If you lose power without explicitly saving your work, you
will likely lose data

3. Names for different sizes of data
When choosing a new computer we come across terms such as "1 TB hard drive" and "4 GB
RAM", and to the uninitiated, this can be somewhat disconcerting. Data in a computer is
represented in a series of bits (binary digits) or ones and zeroes. Since the birth of computers,
bits have been the language that control the processes that take place inside that mysterious black
box called your computer.
Understanding what is bigger or faster, and how much so, will play a role in what you buy and how cost
effective it is. In the image shown, various specifications that are commonly seen are shown.
What do they mean? Does this indicate good or bad?
What is better, 8 Mbps (also written as 8 Mbit/s) or 2 MBps?
Bit (Binary Digit)
A bit is simply a 1 or a 0. A true or a false. It is the most basic unit of data in a computer.
It's like the dots and dashes in Morse code for a computer. It's also called machine language.
Any data of any kind that is stored in the computer or transmitted by the computer is ultimately made up of bits
. A program (software) written in a high-level (human readable) language like Java or C++ is converted to
machine language (bits) before the computer can run it.
A bitcan representanythingwe want,perhapsyesandno,butit hasonlytwo possible values.So,torepresentmore
things,we have alwaysgroupedbitsintolargerchunks.The numberof bitsdeterminessome maximumnumberof
unique combinationsof bits. A groupof 8 bitshas 256 (28) possible unique combinations.
Each of those combinationscanhave itsownmeaningthatwe agree upon.
way.]

4. Byte
A byte is a basic unit of measurement of information storage or transmission that consists of 8 bits.
It can be used to represent letters and numbers – up to 256 of each.
Twitter allows messages of up to 140 characters (Bytes), while SMS (Short Message Service) or cell phone textin
allows up to 160 Bytes. Most text only emails can be measured in Bytes, i.e., the emails are relatively small.

5. Word
The size of a computer "word" is variable. It is based upon how many bits the CPU can read at one time,
and that has changed over time. We are currently (c. 2011) in a transition from 32-bit systems to 64-bit systems.
concern with this is that a 32-bit system can directly support (address) at most 4 GigaBytes of RAM (232).
To use more RAM we need to "trick" the computer or get a 64-bit system. Oddly, most current computers
are also right around 4 GB of RAM, so this knowledge is of immediate value in purchasing a new system.
You want a 64-bit system!
We got a bit ahead of ourselves there, so let's back up...
KB or KiloByte
One KB is 1000 Bytes, at least if you don't wear the title "geek" as a badge of honor and especially if your in mar
When measuring disk space, one KB is 1024 bytes (210). Obviously, if you were selling a disk drive that could ho
exactly 1000 bytes, it would be to your advantage to market it is a 1KB drive.
A typical word processor document, without a lot of images, is likely to measure in the KB range.
MB or MegaByte
A megabyte is approximately 1000KB. Technically, it is 1024KB (1024 x 1024). Again, the technical value is of
primarily to geeks.
Most digital camera create image that are in the MB range. An 8 MP (megapixel) camera has 8 million sensors, e
representing a pixel or picture element. Each pixel, in turn uses some numbers of bits to represent the various col
"true color" camera has 24 bits (3B) per pixel. Assuming no compression, each image would be 24MB!
GB or GigaByte
A gigabyte is a unit of data storage worth approximately a billion bytes, meaning either 1000MB or the more tech
1024MB (1024 x 1024 x 1024). More often than not in advertising, Gigabytes are presented as 1 billion bytes and
1,073,741,824 (It's only off by 7%.). This explains why a freshly formatted 500GB hard drive shows up at a 450G
instead. Not too long ago many people were discussing RAM and even disk storage in Megabytes. These days, st
become so cheap that having 4-8 gigabytes of RAM is considered the norm.
A DVD holds gigabytes of data, so storing movies on your hard drive will take large chunks of space.
TB
A terabyte is 10244 and is defined as about one trillion bytes, or 1024 gigabytes. Data centers such as those opera

6. Google handle thousands if not millions of terabytes of data each day. As storage becomes cheaper and faster, ter
are becoming a commonly heard term.
Disk drives in in the TB range are common. (You can buy them at Walmart!)
PB or PetaByte
A petabyte is a unit of information or computer storage equal to one quadrillion bytes (10245).
Google process about 24PB of data per day. See map of Google data centers.
By Paul Mullins: constructed image
Measurements of Data Speed
Today there are generally two ways of describing data transfer speeds: in bits per second, or in
bytes per second. As explained above, a byte is made of 8 bits. Network engineers still describe
network speeds in bits per second, while your Internet browser would usually measure a file
download rate in bytes per second. A lower case "b" usually means a bit, while an upper case
"B" represents a byte. Hence, the answer to which is better 8 Mbps or 2 MBps? Is 2 MBps
(which is 16 Mbps). Using a less common, but more clear notation: which is better 8 Mbit/s or 2
MBps? Answer: 2 MBps, since that is 16 Mbit/s. (Marketing people use this confusion to their
advantage, if you're not sure which is intended, ask.)
bps
Known as bits per second, bps was the main way of describing data transfer speeds several
decades ago. Bps was also known as the baud rate, therefore, a 600 baud modem was one which
could transfer data at around 600bps.

7. Kbps
kilobits per second, or 1000 bits per second. (Network folks didn't get caught up in the 1000 vs
1024 problem.) Modern telephone modems operate at 56Kbps.
Mbps
1,000,000 (million) bits per second. Often used in describing Internet download/upload speeds,
as shown above.
Gbps
1,000,000,000 (billion) bits per second. This term is most commonly heard in local area
networks, where the close proximity of machines allows for fast data transfer rates.
Check yourconnection
How do you know if you're getting what you're paying your Internet service provider for? Try
your own system at speedt est.net.
CPU:
Control unit : central nervous system
ALU
CPU works on instructions.200 and more instructions are written
in instruction set. These instructions are stored temporarily in
registers of CPU
Processor speed: emits millions of electric pulses per second (clock
cycles). Several clock cycles are required to fetch,decode and
execute a single program.
Shorter clock cycles more is speed. So processor speed in Mega
Hertz means million(for mega) and cycles per second (for hertz)

8. Ghz means 1000000000(109
)cycles per second or 1000MBcycles
per second
Cpu is called as processor and is 2 inch by 2 inch inserted in socket
given in mother board. It warms up during operations and hence
fan is given.
There are several transistorswhich performs mathematical
operations. Current passed is 1 and current off is zero.
Transistor is located on silicon chip (hence silicon valley). A single silicon
chipcan containthousandsof transistors.A single CPUcontainsalarge numberof chips. In a modern
CPU, however,thatsquare inchcanholdseveral hundredmilliontransistors.Andmore transistors
meansmore calculations
Moore’s Law

9. Gordon moore cofounder of intel predicted that number of
transistors on integrated circuits doubles in every 18 to 24 months
in 1965.Corollary is that prices get halved every 18 to 24 months
Registers of cpu cant contain all information. Fetchingdata from
harddisk all the time results in big mismatch (CPU process at say 5
nanosecond per byte and HDD reads at 5 microsecond/byte. i.e for
byte of hdd cpu can process 1000bytes.
To overcome this RAM is introduced.
Is CD Random for access????
ROM-PROM- Flash
Main memory (RAM)
Cache Memory
Control Unit ALU
……variousregisters…….
.

10. Read only memory: you cant alter this. i.e. you cant write over this.
E.g. booting of system instructions.
Primary memory has storage areas called locations or cells. Each
location has fixed number of bits called word length.
Why 64 bit is better than 8 bit?
Imagine the speed of traffic if highway is of 4 lanes, 8 lanes, 16
lanes or 64 lanes.
Even fetching data from RAM is not matching with speed of
processor. It is still 10 times slower. An extremely fast, and small
memory is introduced between CPU and main memory. It is called
as Cache memory. It stores very active instructions.
BUSES
To enable flow of traffic from memory to CPU buses are used. It
may be 8 ,16,32bits to connect cpu and memory(main).