Personal computer
A personal computer (PC)
is a general-purpose computer whose
size, capabilities, and price make it feasible for individual use. PCs are
intended to be operated directly by an end-user with only a
general knowledge of computers, rather than by a computer expert or technician.
"Computers were invented to 'compute': to solve complex mathematical
problems," but today, due to media dependency and the everyday use of
computers, it is seen that "'computing' is the least important thing
computers do."[1] The
computer time-sharing models
that were typically used with larger, more expensive minicomputer and mainframe systems,
to enable them be used by many people at the same time, are not used with PCs.
A range of software applications
("programs") are available for personal computers including, but are
not limited to, word
processing, spreadsheets, databases, web browsers and email, digital media playback, video games and many
personal productivity and special-purpose software applications. In the 2010s,
PCs are typically connected to the Internet, allowing access
to the World Wide
Weband other resources. Personal computers may be connected to a local area
network (LAN), either by a cable or a wireless connection. In
the 2010s, a PC may be:
·
a multi-component desktop
computer, designed for use in a fixed location
·
a laptop computer,
designed for easy portability or
·
a tablet computer, designed
to be hand-held.
In the 2010s, PCs run using an operating system (OS),
such as Microsoft
Windows 10, Linux (and
the various operating systems based on it), or Macintosh (OS X).
Early computer owners in the
1960s, invariably institutional or corporate, had to write their own programs
to do any useful calculations with the machines, which even did not include an
operating system. The very earliest microcomputers, equipped with a front panel, required
hand-loading of a "bootstrap"
program to load programs from external storage (paper tape ("punched
tape"), tape
cassettes, or eventually diskettes). Before long, automatic booting
from permanent read-only
memory (ROM) became universal. In the 2010s, users have access
to a wide range of commercial
software, free software ("freeware") and free and
open-source software, which are provided in ready-to-run or
ready-to-compile form.
Software for personal computers, such as applications ("apps") and video games, are typically
developed and distributed independently from the hardware or OS manufacturers,
whereas software for many mobile phones and other portable systems is approved
and distributed through a centralized online store.[2][3]
Since the early 1990s, Microsoft operating
systems and Intel hardware have
dominated much of the personal computer market, first with MS-DOS and then with Windows. Alternatives to
Microsoft's Windows operating systems occupy a minority share of the industry.
These include Apple's OS X and free
open-source Unix-like operating
systems such as Linux and BSD. AMD provides the main alternative to
Intel's processors. ARM architecture processors
"sold 15 billion microchips in 2015, which was more than US rival Intel
had sold in its history"[4] and
ARM-based smartphones and tablets, those are also
effectively personal computers – though not usually described as
such – now outnumber traditional PCs (that are by now predominantly
Intel-based while a small minority is AMD-based).
Hardware
An exploded view of
a modern personal computer and peripherals (some of which are optional):
1. Scanner
2. CPU (Microprocessor)
4. Expansion
cards (graphics
cards, etc.)
5. Power supply
6. Optical disc drive
8. Motherboard
9. Speakers
10. Monitor
11. System
software
13. Keyboard
14. Mouse
16.
Printer
Main article: Personal
computer hardware
Computer hardware is
a comprehensive term for all physical parts of a computer, as distinguished
from the data it contains or operates on, and the software that provides
instructions for the hardware to accomplish tasks. The boundary between
hardware and software has become blurred, with the existence of firmware that
is software "built into" the hardware. For example, a 2010-era LCD
display screen contains a small computer inside. Mass-market consumer computers
use highly standardized components and so are simple for an end user to assemble
into a working system. Most 2010s-era computers only require users to plug in
the power supply, monitor, and other cables. A typical desktop computer consists
of a computer case (or
"tower"), a metal chassis that holds the power supply, motherboard, hard disk drive, and often
an optical disc
drive. Most towers have empty space where users can add additional
components. External devices such as a computer monitor or visual
display unit, keyboard, and a pointing device (mouse) are usually found
in a personal computer.
The motherboard connects
all processor, memory and peripheral devices together. The RAM, graphics card and processor are in
most cases mounted directly onto the motherboard. The central
processing unit (microprocessor chip) plugs into a CPU socket, while the
memory modules plug into corresponding memory sockets. Some motherboards have
the video display adapter, sound and other peripherals integrated onto the
motherboard, while others use expansion slots for
graphics cards, network cards, or other I/O devices. The
graphics card or sound card may employ a break out box to keep
the analog parts away from the electromagnetic
radiation inside the computer case. Disk drives, which provide
mass storage, are connected to the motherboard with one cable, and to the power
supply through another cable. Usually, disk drives are mounted in the same case
as the motherboard; expansion chassis are also made for additional disk
storage.
For large amounts of data, a tape drive can be
used or extra hard disks can be put together in an external case. The keyboard
and the mouse are external devices plugged into the computer through connectors
on an I/O panel on the back of the computer case. The monitor is also connected
to the input/output (I/O) panel, either through an onboard port on the
motherboard, or a port on the graphics card. Capabilities of the personal
computers hardware can sometimes be extended by the addition of expansion cards connected
via an expansion bus.
Standard peripheral buses often used for adding expansion cards in personal
computers include PCI, PCI Express (PCIe),
and AGP (a
high-speed PCI bus dedicated to graphics adapters, found in older computers).
Most modern personal computers have multiple physical PCI Express expansion
slots, with some of the having PCI slots as well.
Computer case
Main article: Computer case
An empty ATX case lying on its side
A computer case is an
enclosure that contains the main components of a computer. They are usually
constructed from steelor aluminum combined
with plastic, although other
materials such as wood have been used
for specialized units. Cases are available in different sizes and shapes; the
size and shape of a computer case is usually determined by the configuration of
the motherboard that it
is designed to accommodate, since this is the largest and most central
component of most computers. The most popular style for desktop computers is ATX, although microATX and similar
layouts became very popular for a variety of uses. Companies like Shuttle Inc. and AOpen have
popularized small cases, for which FlexATX is the most
common motherboard size. In the 1990s, desktop computer cases were larger and
taller than 2010-era computer cases.
Power supply unit
Main article: Power supply
unit (computer)
Computer power supply unit
with top cover removed
The power supply unit (PSU)
converts general-purpose mains AC electricity to direct current (DC)
for the other components of the computer. The rated output capacity of a PSU
should usually be about 40% greater than the calculated system power
consumption needs obtained by adding up all the system components. This
protects against overloading the supply, and guards against performance
degradation.
Processor
Main article: Central
processing unit
The central
processing unit, or CPU, is a part of a computer that executes
instructions of a software program. In newer PCs, the
CPU contains over a million transistors in one integrated circuit chip called
the microprocessor.
In most cases, the microprocessor plugs directly into the motherboard. The chip
generates so much heat that the PC builder is required to attach a special
cooling device to its surface; thus, modern CPUs are equipped with a fan attached via heat sink. IBM PC compatible computers
use an x86-compatible
microprocessor, manufactured by Intel, AMD, VIA Technologies or Transmeta. Apple Macintosh
computers were initially built with the Motorola 680x0 family
of processors, then switched to the PowerPC series; in
2006, they switched to x86-compatible processors made by Intel.
Motherboard
Main article: Motherboard
A motherboard without
processor, memory and expansion cards, cables
The motherboard, also referred
to as system board or main board, is the primary circuit board within
a personal computer, and other major system components plug directly into it or
via a cable. A motherboard contains a microprocessor, the CPU supporting
circuitry (mostly integrated
circuits) that provide the interface between memory and input/output
peripheral circuits, main memory, and facilities for initial setup of the
computer immediately after power-on (often called boot firmware or, in IBM
PC compatible computers, a BIOS or UEFI). In many portable and embedded
personal computers, the motherboard houses nearly all of the PC's core
components. Often a motherboard will also contain one or more peripheral buses
and physical connectors for expansion purposes. Sometimes a secondary daughter board is
connected to the motherboard to provide further expandability or to satisfy
space constraints.
Main memory
Main article: Primary
storage
1 GB DDR SDRAM PC-3200
module
A PC's main memory is a fast primary storage device
that is directly accessible by the CPU, and is used to store the currently
executing program and immediately needed data. PCs use semiconductor random access
memory (RAM) of various kinds such as DRAM,
SDRAM or SRAM as
their primary storage. Which exact kind is used depends on cost/performance
issues at any particular time. Main memory is much faster than mass storage
devices like hard disk
drives or optical discs, but is
usually volatile,
meaning that it does not retain its contents (instructions or data) in the absence
of power, and is much more expensive for a given capacity than is most mass
storage. As a result, main memory is generally not suitable for long-term or
archival data storage.
Hard disk
Main article: Hard disk
drive
A Western Digital 250 GB
hard disk drive
Mass storage devices store
programs and data even when the power is off; they do require power to perform
read and write functions during usage. Although flash memory has
dropped in cost, the prevailing form of mass storage in personal computers is
still the hard disk
drive. If the mass storage controller provides additional ports for
expandability, a PC may also be upgraded by the addition of extra hard disk or optical disc
drives. For example, BD-ROMs, DVD-RWs, and various
optical disc recorders may all be added by the user to certain PCs. Standard
internal storage device connection interfaces are PATA, Serial ATA and SCSI. Solid state drives (SSDs) are a much faster replacement for
traditional mechanical hard disk drives, but are also more expensive in terms
of cost per gigabyte.
Visual display unit
Main article: Visual
display unit
A visual display unit,
computer monitor or just display, is a piece of electrical
equipment, usually separate from the computer case, which displays
visual images without
producing a permanent computer record. A display device was usually either a CRT in the 1980s, but
by the 2000s, flat panel displays such as a TFT LCD had largely
replaced the bulkier, heavier CRT screens. Multi-monitor setups
are quite common in the 2010s, as they enable a user to display multiple
programs at the same time (e.g., an email inbox and a word processing program).
The display unit houses an electronic
circuitry that generates its picture from signals received
from the computer. Within the computer, either integral to the motherboard or
plugged into it as an expansion card, there is
pre-processing circuitry to convert the microprocessor's output data to a format
compatible with the display unit's circuitry. The images from computer monitors
originally contained only text, but as graphical
user interfaces emerged and became common, they began to
display more images and multimedia content. The term "monitor" is
also used, particularly by technicians in broadcasting television,
where a picture of the broadcast data is displayed to a highly standardized reference monitor for
confidence checking purposes.
Video card
Main article: Video card
An ATI Radeon video card
The video card—otherwise
called a graphics card, graphics adapter or video adapter—processes the graphics
output from the motherboard and transmits it to the display. It is an essential
part of modern multimedia-enriched computing. On older models, and today on
budget models, graphics circuitry may be integrated with the motherboard, but
for modern and flexible machines, they are connected by the PCI, AGP,
or PCI Express interface.
When the IBM PC was introduced, most existing business-oriented personal
computers used text-only display adapters and had no graphics capability. Home
computers at that time had graphics compatible with television signals, but
with low resolution by modern standards owing to the limited memory available
to the eight-bit processors available at the time.
Keyboard
Main article: Keyboard
(computing)
A "Model M" IBM
computer keyboard from the early 1980s. Commonly called the "Clicky
Keyboard" due to its buckling spring key
spring design, which gives the keyboard its iconic 'Click' sound with each
keystroke.
A keyboard is
an arrangement of buttons that each correspond to a function, letter, or
number. They are the primary devices used for inputting text. In most cases,
they contain an array of keys specifically organized with the corresponding
letters, numbers, and functions printed or engraved on the button. They are
generally designed around an operators language, and many different versions
for different languages exist. In English, the most common layout is the QWERTY layout, which
was originally used in typewriters.
They have evolved over time, and have been modified for use in computers with
the addition of function keys, number keys, arrow keys, and keys specific to an
operating system. Often, specific functions can be achieved by pressing
multiple keys at once or in succession, such as inputting characters with
accents or opening a task manager. Programs use keyboard shortcuts very
differently and all use different keyboard shortcuts for different program
specific operations, such as refreshing a web page in a web browser or
selecting all text in a word processor. In addition to the alphabetic keys
found on a typewriter, computer keyboards typically have a numeric keyboard and
a row of function keys and
special keys, such as CNTRL, ALT, DEL and Esc.
Mouse
Main article: Mouse
(computing)
A selection of computer mice
built between 1986 and 2007
A computer mouse is a small
handheld device that users hold and slide across a flat surface, pointing at
various elements of a graphical user interface with an on-screen cursor,
and selecting and moving objects using the mouse buttons. Almost all modern
personal computers include a mouse; it may be plugged into a computer's rear
mouse socket, or as a USB device,
or, more recently, may be connected wirelessly via an USB dongle or Bluetooth
link. In the past, mice had a single button that users could press down on the
device to "click" on whatever the pointer on the screen was hovering
over. Modern mice have two, three or more buttons, providing a "right
click" function button on the mouse, which performs a secondary action on
a selected object, and a scroll wheel, which users can rotate using their
fingers to "scroll" up or down. The scroll wheel can also be pressed
down, and therefore be used as a third button. Some mouse wheels may be tilted
from side to side to allow sideways scrolling. Different programs make use of
these functions differently, and may scroll horizontally by default with the
scroll wheel, open different menus with different buttons, etc. These functions
may be also user-defined through software utilities. Mice traditionally
detected movement and communicated with the computer with an internal
"mouse ball", and used optical encoders to detect
rotation of the ball and tell the computer where the mouse has moved. However,
these systems were subject to low durability, accuracy and required internal
cleaning. Modern mice use optical technology to directly trace movement of the
surface under the mouse and are much more accurate, durable and almost
maintenance free. They work on a wider variety of surfaces and can even operate
on walls, ceilings or other non-horizontal surfaces.
Other components
A proper ergonomic design of a
personal computer workplace is necessary to prevent repetitive strain injuries,
which can develop over time and can lead to long-term disability.[71]
All computers require either
fixed or removable storage for their operating system, programs and
user-generated material. Early home computers used compact audio cassettes for
file storage; these were at the time a very low cost storage solution, but were
displaced by floppy disk drives when manufacturing costs dropped, by the
mid-1980s. Initially, the 5.25-inch and 3.5-inch floppy drives were the
principal forms of removable storage for backup of user files and distribution
of software. As memory sizes increased, the capacity of the floppy did not keep
pace; the Zip drive and
other higher-capacity removable media were introduced but never became as
prevalent as the floppy drive. By the late 1990s, the optical drive, in CD and later DVD and Blu-ray Disc forms,
became the main method for software distribution, and writeable media provided
means for data backup and file interchange. As a result, floppy drives became
uncommon in desktop personal computers since about 2000, and were dropped from
many laptop systems even earlier.[note 1]
A second generation of tape
recorders was provided when videocassette
recorders were pressed into service as backup media for larger
disk drives. All these systems were less reliable and slower than purpose-built
magnetic tape drives. Such tape drives were uncommon in consumer-type personal
computers but were a necessity in business or industrial use. Interchange of
data such as photographs from digital cameras is greatly expedited by
installation of a card reader,
which is often compatible with several forms of flash memory devices.
It is usually faster and more convenient to move large amounts of data by
removing the card from the mobile device, instead of
communicating with the mobile device through a USB interface.
A USB flash drive performs
much of the data transfer and backup functions formerly done with floppy
drives, Zip disks and other
devices. Mainstream operating systems for personal computers provide built-in
support for USB flash drives, allowing interchange even between computers with
different processors and operating systems. The compact size and lack of moving
parts or dirt-sensitive media, combined with low cost and high capacity, have
made USB flash drives a popular and useful accessory for any personal computer
user.
The operating system can
be located on any storage, but is typically installed on a hard disk or
solid-state drive. A Live CD represents
the concept of running an operating system directly from a CD. While this is
slow compared to storing the operating system on a hard disk drive, it is
typically used for installation of operating systems, demonstrations, system
recovery, or other special purposes. Large flash memory is currently more
expensive than hard disk drives of similar size (as of mid-2014) but are
starting to appear in laptop computers because of their low weight, small size
and low power requirements. Computer communications involve internal modem cards, modems, network adapter cards, and routers.
Common peripherals and
adapter cards include headsets, joysticks, microphones, printers, scanners, sound adapter cards(as a
separate card rather than located on the motherboard), speakers and webcams.
5
Common Computer Problems & Solutions
You're working away at your
computer when suddenly, up comes an error message or worse, your
computer comes to a screeching halt. Deciphering what computer problemsyou have
and how to fix them can be difficult, especially if you don't know as much as
you'd like about your PC. Here are five common computer problems that system repair software can
help you fix.
Blue
Screen of Death (BSoD)
Many people think of blue as a calming color; however, when it comes up on your computer screen with a bunch of white text, it probably has the opposite effect. The blue screen of death (BSoD or STOP Error) may appear to be one of the scariest computer problems you'll come across. However, all your computer may need is for you to reboot it. This STOP error appears on your screen for a variety of reasons: failing hardware, damaged software, corrupt DLL files, problems with drivers and more. The remedy for a blue screen of death depends on the original problem. The screen provides you with codes that can help you identify and fix your computer problems.
Many people think of blue as a calming color; however, when it comes up on your computer screen with a bunch of white text, it probably has the opposite effect. The blue screen of death (BSoD or STOP Error) may appear to be one of the scariest computer problems you'll come across. However, all your computer may need is for you to reboot it. This STOP error appears on your screen for a variety of reasons: failing hardware, damaged software, corrupt DLL files, problems with drivers and more. The remedy for a blue screen of death depends on the original problem. The screen provides you with codes that can help you identify and fix your computer problems.
Missing
DLL File
Dynamic-Link Library (DLL) files house information for your operating system on how to perform certain functions. Occasionally, your computer loses DLL files or something damages them. When your PC can't read the particular DLL file, it doesn't know how to respond in certain situations. You may have a missing or corrupt DLL file if you receive an error message every time you perform a certain function, such as saving. If your computer problems are stemming from missing and damaged DLL files, you can restore them by downloading them back onto your PC.
Dynamic-Link Library (DLL) files house information for your operating system on how to perform certain functions. Occasionally, your computer loses DLL files or something damages them. When your PC can't read the particular DLL file, it doesn't know how to respond in certain situations. You may have a missing or corrupt DLL file if you receive an error message every time you perform a certain function, such as saving. If your computer problems are stemming from missing and damaged DLL files, you can restore them by downloading them back onto your PC.
Applications
That Won't Install
If you're having trouble with an application not installing, it may be because your computer doesn't have enough hard drive space. If this is the case, you need to free up some space. This is one of the computer problems that's, well, least problematic. You can free up some hard drive space by getting rid of files and folders you don't need. These may be temporary files, duplicate files or data for software you've uninstalled.
If you're having trouble with an application not installing, it may be because your computer doesn't have enough hard drive space. If this is the case, you need to free up some space. This is one of the computer problems that's, well, least problematic. You can free up some hard drive space by getting rid of files and folders you don't need. These may be temporary files, duplicate files or data for software you've uninstalled.
Applications
Run Slowly
There are several reasons software might be running at turtle speed. You may have computer problems that involve your operating system or an application, your operating system might be missing updates or your computer doesn't have enough hard drive space. If you don't have enough hard drive space, you can scan, clean and optimize your hard drive.
There are several reasons software might be running at turtle speed. You may have computer problems that involve your operating system or an application, your operating system might be missing updates or your computer doesn't have enough hard drive space. If you don't have enough hard drive space, you can scan, clean and optimize your hard drive.
Abnormal
Applications Behavior
Computer problems that involve applications acting strangely oftentimes leave you wondering what has happened. Your application has been working just fine, but now, seemingly without reason, it is doing something strange.
Computer problems that involve applications acting strangely oftentimes leave you wondering what has happened. Your application has been working just fine, but now, seemingly without reason, it is doing something strange.
For instance, your Word document will no longer show the top margin of your
document. It still says it's there, and when you print it, there's not a
problem. You just can't see it on your monitor. If this is happening, you may
want to restart your computer. Conducting an internet search for the type of
problem you're experiencing or consulting your user manual may help you as
well.
Using System Repair Software
If you have computer problems,
chances are, system repair software can help you fix it. Most of these
applications can repair operating system problems that lead to the Blue Screen
of Death. They can also replace missing or damaged DLL files. System repair
software can also free up space you need for another application, and it can
optimize your computer so it runs faster. It may even identify problems you're
having with applications, but it depends on the software you use and the
application that's having problems.
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