COMPUTER
GUIDE: DEFINITION, TYPES, SPECIFICATIONS, EXAMPLES, COMPONENTS & FULL
DETAILS.
A computer is a machine that can be instructed to
carry out various of
arithmetic or logical operations automatically
via computer programming.
Now a
days, Modern computers have the ability to follow generalized sets of
operations, called programs. These
programs enable computers to perform an extremely wide range of tasks.
A
"complete" computer including the hardware, the operating
system (main software), and peripheral equipment required and used
for "full" operation can be referred to as a computer system.
This
term may as well be used for a group of computers that are connected and work
together, in particular a computer network or computer cluster.
Computers
are used as control systems for a wide variety of industrial and consumer
devices.
This
includes simple special purpose devices like microwave ovens and remote
controls,
factory devices such as industrial robots and computer-aided design and also general purpose devices like personal
computers and mobile devices such as smartphones.
The Internet is run on computers and
it connects hundreds of millions of other computers and their users every
single day.
Peripheral devices
include input devices (keyboards, mice, joystick, etc.), output devices
(monitor screens, printers, etc.), and input/output devices that perform both
functions (e.g., the 2000s-era touchscreen).
Peripheral devices allow information to be retrieved from an external
source and they enable the result of operations to be saved and retrieved.
Types
Analog
Computers
During
the first half of the 20th century, many scientific computing needs were met by
increasingly sophisticated analog computers, which used a direct mechanical or electrical
model of the problem as a basis for computation.
However,
these were not programmable and generally lacked the versatility and accuracy
of modern digital computers.
The
first modern analog computer was a tide-predicting machine, invented by Sir William
Thomson in
1872.
The differential
analyser, a
mechanical analog computer designed to solve differential equations by
integration using wheel-and-disc mechanisms, was conceptualized in 1876
by James Thomson, the
brother of the more famous Lord Kelvin.
Digital computers
·
Electromechanical
Early
digital computers were electromechanical; electric switches drove mechanical
relays to perform the calculation.
These
devices had a low operating speed and were eventually superseded by much faster
all-electric computers, originally using vacuum tubes.
The Z2, created by German
engineer Konrad Zuse in
1939, was one of the earliest examples of an electromechanical relay computer.
In
1941, Zuse followed his earlier machine up with the Z3, the world's first working electro-mechanical programmable, fully automatic digital
computer. The Z3 was built with 2000 relays, implementing a 22 bit word length that operated at
a clock frequency of about 5–10 Hz.
·
Colossus
Colossus
was the world's first electronic digital programmable computer.
It
used a large number of valves (vacuum tubes).
It
had paper-tape input and was capable of being configured to perform a variety
of boolean logical operations on its data, but it was not Turing-complete.
Nine
Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines
in total). Colossus Mark I contained 1,500 thermionic valves (tubes), but Mark
II with 2,400 valves, was both 5 times faster and simpler to operate than Mark
I, greatly speeding the decoding process.
· ENIAC
The ENIAC (Electronic Numerical
Integrator and Computer) was the first electronic programmable computer built
in the U.S. Although the ENIAC was similar to the Colossus, it was much faster,
more flexible, and it was Turing-complete.
The
programmers of the ENIAC were six women, often known collectively as the
"ENIAC girls".
It
combined the high speed of electronics with the ability to be programmed for
many complex problems.
It could add or subtract 5000 times a second,
a thousand times faster than any other machine. It also had modules to
multiply, divide, and square root.
High speed memory was limited to 20 words
(about 80 bytes). Built under the direction of John Mauchly and J. Presper Eckert at
the University of Pennsylvania, ENIAC's development and construction lasted
from 1943 to full operation at the end of 1945.
The machine was huge, weighing 30 tons, using 200 kilowatts of
electric power and contained over 18,000 vacuum tubes, 1,500 relays, and
hundreds of thousands of resistors, capacitors, and inductors.
Hybrid
computers
The above picture is Polish Hybrid
computer WAT 1001.
Hybrid computers are computers that exhibit features of analog computers and digital computers.
The digital component normally serves as the
controller and provides logical and numerical operations, while the analog component often serves as a solver of differential equations and
other mathematically complex equations.
The first desktop hybrid computing system was
the Hycomp 250, released by Packard Bell in 1961. Another early
example was the HYDAC 2400, an integrated hybrid computer released by EAI in 1963.
A supercomputer is
a computer with
a high level of performance as compared to a general-purpose computer.
The performance of a supercomputer is commonly measured
in floating-point operations
per second (FLOPS)
instead of million
instructions per second (MIPS).
Since 2017, there are supercomputers which can perform over
1017 FLOPS (a hundred quadrillion FLOPS, 100
petaFLOPS or 100 PFLOPS).
Since November 2017, all of the world's fastest 500
supercomputers run Linux-based operating systems.
Additional research is being conducted in the United States,
the European
Union, Taiwan, Japan, and China to
build faster, more powerful and technologically superior exascale supercomputers.
A mainframe computer,
informally called a mainframe or big iron, is a computer used primarily by
large organizations for critical applications, bulk data processing such as the
census and
industry and consumer statistics, enterprise resource planning,
and large-scale transaction
processing.
A mainframe computer is larger and has more processing power
than some other classes of computers, such as minicomputers, servers, workstations,
and personal
computers.
Mainframe computers are more often used as servers.
Above picture is A PDP-11, model 40, an
early member of DECs 16-bit minicomputer family, on display at the Vienna Technical Museum.
A minicomputer, or colloquially mini, is a class of smaller computers that was developed in
the mid-1960s.
minicomputer
as a machine costing less than US $25,000 with an
input-output device such as a teleprinter and at least four thousand words of
memory, that is capable of running programs in a higher level language, such
as Fortran or BASIC.
Above
picture is Raspberry Pi, a popular microcomputer.
A microcomputer is
a small, relatively inexpensive computer with a microprocessor as
its central
processing unit (CPU).
It includes a microprocessor, memory and minimal input/output (I/O)
circuitry mounted on a single printed circuit board (PCB).
Microcomputers became popular in the 1970s and 1980s with the
advent of increasingly powerful microprocessors.
Home
computers
Home computers were a class of microcomputers that entered the
market in 1977 and became common during the 1980s.
They were marketed to consumers as affordable
and accessible computers that, for the first time, were intended for the use of
a single nontechnical user.
These computers were a distinct market segment that
typically cost much less than business, scientific or engineering-oriented
computers of the time such as those running CP/M or the IBM PC, and were
generally less powerful in terms of memory and expandability.
However, a home computer often had better graphics and sound than
contemporary business computers.
Their most common uses were playing video games, but
they were also regularly used for word processing, doing homework, and programming.
Other types of Computer
A desktop computer is
a personal
computer designed for regular use at a single location on or
near a desk or
table due to its size and power
requirements.
Desktop computer Types
Full-sized
Full-sized desktops are characterized by
separate display and processing components.
These components are connected to each other
by cables or wireless
connections.
They often come in a tower form
factor.
These computers are easy to customize and
upgrade per user requirements, e.g. by expansion card.
All-in-one desktop
The above picture is kayro II all-in-one
computer.
An all-in-one desktop
computer integrates the system's internal components into the same case as the
display, thus occupying a smaller footprint (with fewer cables) than desktops
that incorporate a tower.
The all-in-one form factor was popular during
the early 1980s for personal computers intended for professional use such as
the Kaypro II, Osborne
1, TRS-80 Model II and Compaq Portable.
Compact
The
above picture is Acer AspireRevo nettop compact desktop.
Compact desktops are reduced in physical
proportions compared to full-sized desktops.
They are typically small-sized, inexpensive,
low-power computers designed for basic tasks such as web browsing,
accessing web-based
applications, document processing, and audio/video
playback.
Hardware specifications and processing power
are usually reduced and hence make them less appropriate for running complex or
resource-intensive applications.
A nettop is an example of a compact desktop.
Home theater
These desktops are
connected to home entertainment systems and typically used for amusement
purpose.
They come with high
definition display, video graphics, surround sound and TV tuner systems to
complement typical PC features.
The three personal computers
referred to by Byte Magazine as the "1977 Trinity" of home computing:
The Commodore PET, the Apple II, and the TRS-80 Model I.
A personal computer (PC) is a multi-purpose computer whose size,
capabilities, and price make it feasible for individual use.
Personal computers are intended to be operated directly by
an end
user, rather than by a computer expert or technician.
Unlike large, costly minicomputers and mainframes, time-sharing by
many people at the same time is not used with personal computers.
The above picture is Amiga 1000(1985) first multimedia &
personal computer..
A multimedia computer is
a computer that
is optimized for high multimedia performance.
The Amiga
1000 from Commodore International has
been called the first multimedia computer.
A gaming computer,
also known as a gaming PC or gaming rig, is a personal computer designed
for playing video
games that require a high amount of computing power.
Keyboard Computer
The above picture is Sinclair zx spectrum
keyboard computer.
A keyboard computer is
a computer which contains all of the regular components of a personal computer, except for a screen, in the same housing as the keyboard.
The power supply is typically external and connects
to the computer via an adapter cable.
The motherboard is specially designed to fit
inside, and the device is larger than most standard keyboards.
Additional peripheral components such as
a monitor are connected to the computer via external ports.
Usually a minimum of storage devices, if any, is built in.
Most home computers of the late 1970s and
during the 1980s were keyboard computers, the Sinclair ZX Spectrum and most models of the Atari ST, Commodore 64 and Amiga being
prime examples.
The above picture is The Compaq Portable, one
of the first portable IBM
PC compatible systems.
A portable computer is
a computer designed
to be easily moved
from one place to another and included a display and keyboard.
The first commercially sold portable was the 50-pound
(23 kg) IBM
5100, introduced 1975.
The
above Pictures are of LunaTik, a machined wristband attachment for
the 6th-generation iPod Nano and Google
Glass, Google's head-mounted display, which was launched in
2013.
A wearable computer, also known as a wearable or body-borne computer, is
a computing device worn on the body.
Wearables
are typically worn on the wrist (e.g. fitness trackers), hung from the neck
(like a necklace), strapped to the arm or leg (smartphones when exercising), or
on the head (as glasses or a helmet), though some have been located elsewhere
(e.g. on a finger or in a shoe).
Devices carried in a pocket or bag – such
as smartphones.
Mobile computing is human–computer interaction in
which a computer is
expected to be transported during normal usage, which allows for the
transmission of data, voice, and video. Mobile computing involves mobile
communication, mobile hardware, and mobile software.
Communication issues include ad hoc networks and
infrastructure networks as well as communication properties, protocols, data
formats, and concrete technologies.
Hardware includes mobile devices or device
components. Mobile software deals with the characteristics and requirements of
mobile applications.
The above picture is of Apple's iPad (left) and Amazon's Fire (right), two
popular tablet computers.
A tablet computer,
commonly shortened to tablet, is a mobile device,
typically with a mobile
operating system and touchscreen display
processing circuitry,
and a rechargeable
battery in a single, thin and flat package.
Tablets, being computers, do what other personal computers do,
but lack some input/output (I/O)
abilities that others have.
Modern tablets largely resemble modern smartphones, the
only differences being that tablets are relatively larger than smartphones,
with screens 7 inches (18 cm) or larger, measured diagonally, and may not
support access to a cellular
network.
Single-board computer (SBC)
The Raspberry Pi is a low-cost single-board computer used
to teach computer science.
A single-board computer (SBC)
is a complete computer built
on a single circuit board,
with microprocessor(s), memory, input/output (I/O) and other
features required of a functional computer.
Single-board computers are commonly made as
demonstration or development systems, for educational systems, or for use
as embedded computer controllers.
A plug computer is
an external device, often configured for use in the home or office
as a compact computer.
The name is derived from the small configuration of such
devices; they are often enclosed in an AC power plug or AC adapter.
Quantum Computer
Computers that perform quantum computations are known as quantum computers.
Quantum computing is the use of quantum phenomena adapter superposition and entanglement to perform computation.
Quantum computers are believed to be able to solve certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers.
Desktop replacement computer (DTR)
The above picture is A Clevo x7200 desktop
replacement computer.
A desktop replacement computer (DTR) is a personal computer that
provides the full capabilities of a desktop computer while
remaining mobile.
Rugged Computer
A rugged, or ruggedized computer is a computer specifically designed to operate reliably in harsh
usage environments and conditions, such as strong vibrations, extreme
temperatures and wet or dusty conditions.
This
type of computer mostly used by Militry soldiers.
They
are designed from inception for the type of rough use typified by these
conditions, not just in the external housing but in the internal components and
cooling arrangements as well.
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