computer systems include hardware

7/30/2019 Computer Systems Include Hardware

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Computer systems include hardware, software, and firmware.

Hardware is something you can touch and feelthe physical computer and the parts inside the

computer are examples of hard-ware. The monitor, keyboard, and mouse are hardware components.

Software interacts with the hardware. Windows, Linux, OS X, Microsoft Office, Solitaire, Google Chrome,

Adobe Acrobat Reader, and WordPerfect are examples of software.

A device driver is a special piece of software designed to enable a hardware component. Thedevice

driver enables the operating system to recognize, control, and use the hardware compo-nent. Device

drivers are hardware and operating system specific. For example, a printer requires a specific device

driver when connected to a computer loaded with Windows 98.

A device driver is a special piece of software designed to enable a hardware component. The device

driver enables the operating system to recognize, control, and use the hardware component. Device

drivers are hardware and operating system specific. For example, a printer requires a specific device

driver when connected to a computer loaded with Windows 98.

Adapters are electronic circuit cards that normally plug into an expansion slot on the motherboard.

Other names for an adapter are controller, card, controller card, circuit card, circuit board, and adapter

board. The number of available expansion slots on the mother-board depends on the manufacture.


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A riser board plugs into the motherboard and has its own expansion slots. Adapters can plug into these

expansion slots instead of directly into the moth-erboard.

Memory chips hold applications, part of the operating system, and user documents. Two basic types of

memory are RAM and ROM.

RAM(ran-dom access memory) is volatile memory meaning the data inside the chips is lost when power

to the computer is shut off. When a user types a document in a word processing program, both the

word processing application and the document are in RAM. If the user turns the computer off

without saving the document to a disk or the hard drive, the document is lost because the infor-mation

does not stay in RAM when power is shut off.

ROM(read-only memory) is nonvolatile memory because data stays inside the chip even

when the computer is turned off. ROM chips are sometimes installed on adapters such as a net-work or

video card.


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External Connectivity

A port is a connector on the motherboard or on a separate adapter that allows a device to con-nect to

the computer. Sometimes a motherboard has ports built directly into the motherboard. Motherboards

that have ports built into them are called integrated motherboards.

Male ports have metal pins that protrude from the connector. A male port requires a cable with a

female connector.

Female ports have holes in the connector into which the male cable pins are inserted.

A D-shell connectorhas more pins or holes on top than on the bottom, so a cable connected to the D-

shell connector can only be inserted in one direction and not accidentally flipped upside down. Parallel,

serial, and video ports are examples of D-shell connectors.

A DIN connectoris round with small holes and is normally keyed. When a connector is keyed it has an

extra metal piece or notch that matches with an extra metal piece or notch on the cable, and the cablecan only be inserted into the DIN connector one way. Older keyboard and mouse con-nectors are

examples of DIN connectors.


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A video port is used to connect a monitor. Today, there are two types normally seen and they bothhave

three rows. The older one is a three-row, 15-pin female D-shell.

The 15-pin female connec-tor is used to attach VGA, SVGA, XGA, SXGA, or UXGA monitors. These

monitors have a CRT(cathode ray tube) and are heavier and bulkier than a flat panel monitor. Even

though it can have different types of monitors attached, it is normally referred to as a VGA port.

The newer port is called a DVI port(Digital Visual Interface) and it has three rows of square holes.


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USB stands for Universal Serial Bus. A USB portallows up to 127 devices to transmit at speeds up to

5Gbps (5 billion bits per second) with version 3.0. Compare these speeds to parallel port transfers of

1Mbps (1 million bits per second). Devices that can connect to the USB port include printers, scanners,

mice, keyboards, joysticks, CD drives, DVD drives, tape drives, floppy drives, flight yokes, cameras,

modems, speakers, telephones, video phones, data gloves, and digitizers. In order for the computer to

use the USB port, it must have a Pentium or higher CPU; an oper-ating system that supports USB, such

as Windows 9x or higher, Apple OS X, or *nix (any flavor of Unix) and a chipset that acts as a host

controller. Additional ports can sometimes be found on the front of computer cases.

USB ports and devices come in three versions1.0, 2.0, and 3.0. Version 1.0 supported speeds of

1.5Mbps and 12Mbps. Version 2.0 increased the supported speed to 480Mbps; and Version 3.0 supports

speeds up to 5Gbps. A symbol that looks like a trident is sometimes seen on the USB port or on the USB

cable. A plus sign above one prong identifies a Version 2.0 port, but not all manufacturers use this

symbol. Version 3.0 is sometimes referred to as SuperSpeed USB, and the logo has two Ss on it.


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The parallel portis a 25-pin female D-shell connector used to connect a printer to the computer. Some

motherboards have a small picture of a printer etched over the connector. Parallel ports transfer eight

bits of data at a time to the printer or any other parallel device connected to the parallel port.

A serial port(also known as a COM port, RS-232 port, or an asynchronous (async) port) can be a 9-pin

male D-shell connector or a 25-pin male D-shell connector (on very old computers). Serial ports are used

for a variety of devices including mice, external modems, digitizers, printers, PDAs, and digital cameras.

Serial ports are becoming obsolete for the same reason that parallel ports areUSB ports.


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A sound cardconverts digital computer signals to sound and sound to digital computer signals. A sound

card is sometimes called an audio card and can be integrated into the motherboard or an adapter that

contains several ports. The most common ports include a port for a microphone, one or more ports for

speakers, and an input port for a joystick or MIDI (musical instrument digital interface) device. Examples

of MIDI devices include electronic keyboards and external sound modules.

The joystick port is sometimes known as a game port.

The IEEE 1394 standard is a serial technology developed by Apple Computer. Sometimes it is known as

FireWire or i.Link, which is a Sony trademark. IEEE 1394 portshave been more pre-dominant on Apple

computers, but are now becoming a standard port on PCs. Windows and Apple operating systems

support the IEEE 1394 standard. Many digital products now have an integrated IEEE 1394 port for

connecting to a computer. IEEE 1394 devices include camcorders, cameras, printers, storage devices,

DVD players, CD-R drives, CD-RW drives, tape drives, film readers, speakers, and scanners. Speeds

supported are 100, 200, 400, 800, 1200, 1600, and 3200Mbps. As many as 63 devices (using cable

lengths up to 14 feet) can be connected with FireWire. The IEEE 1394 standard sup-ports hot swapping

(plugging and unplugging devices with the power on), plug and play, and powering low-power devices.

The cable has six wiresfour for data and two for power. Newer IEEE 1394 standards support the use of

RJ-45 and fiber connectors.


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Network Ports

Network ports are used to connect a computer to other computers, including a network server. Two

different network adapters, Ethernet and Token Ring, are available, but most networks use Ethernet

ports. The ports on these adapters can be quite confusing because the connectors are sometimes the

same. A network cable inserts into the network port. Ethernet adapters are the most common type of

NIC(network interface card/controller). They can have a BNC, an RJ-45, a 15-pin female D-shell

connector, or a combination of these on the same adapter.


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The Processors

The processor is also called the CPU (central processing unit) or microprocessor. The processor executes

instructions, performs calculations, and coordinates input/output operations. Each motherboard has

electronic chips that work with the CPU and are designed to exact specifications.\

processor manufacturers today are

Intel,

Motorola,

VIA,

AMD (Advanced Micro Devices, Inc.).

The processors designed by Motorola have been used in Apple computers for years.

Microprocessors come in a variety of speeds. The speed of processors is measured in gigahertz(GHz).

Hertz is a measurement of cycles per second. One hertz equals one cycle per second. One gigahertz is

one billion cycles per second or 1GHz. Older CPUs used megahertz (MHz) as the standard measurement.

One megahertz is one million cycles per second or 1MHz.

The original PC CPU, the 8088 microprocessor, ran at 4.77MHz. Todays microprocessors run at

speeds over 3GHz.

The number of bits processed at one time is the microprocessors register size(word size). Register size

is in multiples of 8 bits (i.e., 8-, 16-, 32-, 64-, or 128-bit). Intels 8086 processors register size was 16 bits

or two bytes. Todays CPUs have register sizes of 64 or 128 bits.

The elec-tronic lines inside the CPU are known as the internal data bus or system bus.


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The external data bus connects the processor to adapters, the keyboard, the mouse, the floppy drive,

the hard drive, and other devices. The external data bus is also known as the external data path. One

can see the external data lines by looking between the expansion slots on the motherboard

Processors have a special component called the ALU(arithmetic logic unit), which does all

the calculations and comparison logic needed by the computer. Refer to Figure 2.1 and see how

the ALU connects to the registers, control unit, and internal bus. Todays processors actually have

two ALUs, but Figure 2.1 simply shows how the buses connect. The control unit coordinates activ-ities

inside the processor. The I/O unit manages data entering and leaving the processor. The reg-isters

within the CPU are a very high speed storage area for 1s and 0s before the bits are processed.

Processors have multiple pipelines(separate internal buses) that operate simultaneously.

A 32- or 64-bit CPU can have separate paths, each of which handles 32 or 64 bits. For exam-ple, the

Pentium has two pipelines.

AMDs Athlon has 9 execution pipelines and the Opteron has 12 pipelines for integers and 17 pipelines

for floating point numbers (numbers that can have a decimal point in it). Intel Pentium 4 and Xeon CPUs

have various models that contain anywhere from 20- to 31-stage pipelines.


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CACHE

An important concept related to CPU speed is keeping data flowing into the processor. Registers

are a type of high speed memory storage inside the CPU and is an integral part of CPU process-ing. The

data or instruction the CPU needs to operate on is usually found in one of three places:

the cache, the motherboard memory (main memory), or the hard drive.

Cache memoryis a very fast type of memory designed to increase the speed of CPU operations.

When cache memory is integrated as part of the CPU, it is called L1 cache. Included in the proces-sor

packaging, but not part of the CPU is L2 cache, which some refer to as on-die cache. Finally,

there is a third level of memory found when using higher end server processors called L3 cache,

which can be located in the CPU housing or on the motherboard. CPU efficiency is increased when

data continuously flows into the CPU. Cache gives the fastest access. If the information is not in

cache, the microprocessor looks for it in the motherboard memory.


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Clocking

The motherboard generates a clock signal that is used to control the transfer of 1s and 0s to the CPU.

Processor clock timing signals go as fast as 100, 133, 166, 200, 266, or 333 MHz (millions of cycles per

second).

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