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TYPES OF COMPUTER |
As technology advances, computers are quickly becoming
more powerful. Those days are gone. Computers come in all shapes and
sizes now, from big and scary to small and cuddly. Sometimes you can’t even
tell if something is a computer or not. Strictly speaking, any device that can
take data, process it according to specific instructions, and then output the
results is a computer. A definition that broad doesn’t clarify much,
however.
In the interests of making things a bit simpler, most
computers can be divided into several categories. Familiar types include
supercomputers, mainframes, workstations, servers, and desktop computers. Each
has a different role in its little computer life.
Based on sizes, computers can be categorized into:
II.
Mainframes
III.
Minicomputers
IV.
Microcomputer
|
Category |
Physical
size |
Number
of instructions executed per second |
Number
of simultaneously connected users |
General
price tag |
|
Personal
Computer (microcomputer) |
Fit in your hand or your desk |
Up to 400 million |
One stand-alone or networked |
Several thousand dollars or less |
|
Minicomputer |
Small cabinet |
Thousands to millions |
Two to 4,000 |
$5,000 -$150,000 |
|
Mainframe |
Partial room to a full room of
equipment |
Millions |
Hundreds to thousands |
$300,000-several
million dollars |
|
Supercomputer |
Full room of equipment |
Millions to billions |
Hundreds to thousands |
Several million dollars and up |
SUPERCOMPUTERSSeymour Cray (FATHER OF SUPERCOMPUTER) is intimately associated with the
history of supercomputers, having designed many of the world's fastest
computers throughout the 1960s,
1970s, and 1980s
for Control Data Corporation and Cray
Research. Supercomputer are the brainiest computers that many people once
pictured when they thought of the word “computer” in all its Orwell Ian
might. Supercomputers are huge, incredibly expensive, extremely fast, and
stunningly complex machines used for large-scale scientific modeling. Capable
of processing more than 64 billion instructions in a single second,
supercomputer are used for applications requiring complex, sophisticated
mathematical calculations. For example, a supercomputer would be used for
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Weather forecasting
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Nuclear energy research
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Petroleum exploration
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Weapons research
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Aircraft designs
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NASA
Their memory hierarchy is very
carefully designed to ensure the processor is kept fed with data and
instructions at all times—in fact, much of the performance difference
between slower computers and supercomputers is due to the memory hierarchy
design and component. Their I/O systems tend to be designed to support high
bandwidth, with latency less of an issue, because supercomputers are not used
for transaction processing.
Vector
processing techniques were first developed
for supercomputers and continue to be used in specialist
high-performance applications. Their operating systems, often variants of UNIX,
tend not to be as sophisticated as those for smaller machines, since
supercomputers are typically dedicated to one task at a time rather than the
multitude of simultaneous jobs that makes up the workload of smaller devices.
THE FASTERS
SUPERCOMPUTERS TODAY
The speed of a supercomputer is
generally measured in FLOPS (floating point operations per second); this
measurement ignores communication overheads and assumes that all processors of
the machine are provided with data and are working at full speed. As of early
2002, the fastest supercomputer is the Earth Simulator at the Yokohama
Institute for Earth Sciences. It is a cluster of 640 custom-designed
8-processor vector processor computers based on the NEC
SX-6 architecture (a total of 5120 processors). It uses a customized version of
the UNIX operating system.
MAINFRAMEAs technology advance, computers
are quickly becoming more powerful. The lines of category become blur and
unclear but generally, computers can be classified based on their sizes and
processing power.
A very large and expensive computer
capable of supporting hundreds, or even thousands, of users simultaneously. In
the hierarchy that starts with a simple microprocessor (in watches, for example)
at the bottom and moves to supercomputers
at the top, mainframes are just below supercomputers. In some ways, mainframes
are more powerful than supercomputers because they support more simultaneous
programs. But supercomputers can execute a single program faster than a
mainframe. The distinction between small mainframes and minicomputers
is vague, depending really on how the manufacturer wants to market its machines.
Supporters claim that mainframes still house 90% of the data
major businesses rely on for mission-critical applications, attributing this to
their superior performance, reliability, scalability, and security compared to
microprocessors
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Mainframes are so named because they were the first built by
placing computer components on a chassis, or “ main frames “.
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Generally found in a special computer room where
environmental such as temperature, dust, and humidity are controlled.
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Have primary storage measured in megabytes or gigabytes.
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Can process data at million instructions per second (MIPS).
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More than 1,000 remote terminals or workstations connected to
mainframes.
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Still used by large corporations, such as banks that are very
large amounts of data to process on big databases.
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Would be used as the main computer.
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The price of these large systems can very from several
hundred thousand to many millions off dollars. Used for processing vast amount
of data quickly, such as bank (ATM), insurance companies, manufacture, airlines
companies, aerospace companies doing complex aircraft design, Internets servers
etc.
A
key characteristic of large computer is that they are designed for multiple
users. For examples, many reservations clerks could be accessing the same
computer at the same time to make reservation for waiting customers.
Examples:
IBM 3090, ICL 39 SX series.
MINICOMPUTERA computer built between about 1963 and 1987, smaller
and less powerful than a mainframe,
typically about the size and shape of a wardrobe, mounted in a single tall rack.
Short word lengths of 8 to 32 bits, limited hardware
and software facilities and small physical size characterized minicomputers.
Their low cost made them suitable for a wide variety of applications such as
industrial control, where a small, dedicated computer, which is permanently
assigned to one application, is needed. In recent years, improvements in device
technology have resulted in minicomputers that are comparable in performance to
large second-generation computers and greatly exceed the performance of first
generation computers.
The processor was typically built using low
integration logic integrated circuits - TTL or maybe ECL, thus
distinguishing it from a microcomputer
which is built around a microprocessor - a processor on a single (or maybe a
few) ICs.
DEC's PDP-1 was the first minicomputer and their
PDP-11 was the most successful, closely followed (in both time and success) by
the VAX (which DEC called a "super minicomputer").
MICROCOMPUTERSMicrocomputers is much
more smaller than minicomputer. Even though it small and cheap but has fairly
limited power. In other sense more micro is personal computer to work with at a
time because it user friendly. That can be defined as computer with storage
capacity 256 kilobytes to several megabytes. There are many different types of
computer - used for many different jobs. Here are some of the popular types of
computer that you can find in use today.
1 POCKET (PALMTOP) COMPUTERA pocket computer has
to have small, light batteries that last a long time so that the whole computer
is light and small enough to be carried around in someone's pocket.
These computers have special operating systems suited to pocket computers.
One problem with small computers is that they don't have full-sized keyboards
attached. Both of the computers in these pictures use special pens and
touch-sensitive screens to enter data as well as a number of small buttons or
keys.
2 LAPTOP COMPUTERS
The person using a laptop should be able to run all the same
software on the laptop as runs on larger, desktop computers as laptop computers
have the same types of operating system as desktop ones. Modern laptops can have
floppy drives, CD-ROM drives and CD re-writers, and even DVD drives. They often
have full-sized, or near-full-sized keyboards and a mouse or a touch-sensitive
mouse pad. The screen is usually a large Liquid Crystal Display (LCD). The main
advantage of a laptop is that the person using it can have all the programs and
data from their desktop computer on a portable computer.
3 MICRO (DESKTOP)
COMPUTERS
The latest operating
system for the Apple Mac (in 2002) is OS X. When people talk about PCs they
usually mean and IBM-compatible' computer based on an Intel (or similar)
microprocessor. The most common operating system for the PC is Microsoft Windows
(latest version Windows XP) although other operating systems are available (e.g.
Linux). These are very popular computers. They are designed to be used on a desk
or table with a separate keyboard and mouse for input
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