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BUS

• A data connection between two or more devices connectedto the computer.

• For example, a bus enables a computer processor to

communicate with the memory or a video card tocommunicate with the memory.

• A bus is capable of being a parallel or serial bus


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• An Industry Standard Architecture bus (ISA bus) allows

additional expansion cards to be connected to a computer'smotherboard.

• It is a standard bus architecture for IBM compatibles.

Introduced in 1981, the ISA bus was designed to support the

Intel 8088 microprocessor for IBM’s first-generation PC.•

In the late 1990s the faster peripheral component interconnect

(PCI).

Soon afterwards, use of the ISA bus began to diminish, and

most IBM motherboards were designed with PCI slots.

• Although there are still a few motherboards being made with

ISA slots, these are generally referred to as the legacy bus

motherboards

ISA (Industry Standard Architecture)


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Block Diagram


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Features

• 16-bit characteristics.

• It supported 16-bit peripheral devices.

• Five devices with 16-bit interrupt request

(IRQ) could be connected at the same time.

• Also, three additional devices could be

connected parallel to five devices with 16-

bit IRQ.

• 16-bit direct memory access (DMA)

channel.

• The CPU clock speed varied from 16 to 20

MHz.


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Advantages

• Low cost• Compatibility• Used widely

Disadvantages

• Low speed• Jumpers and DIP switches

• Becoming out-dated


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The ISA bus allowed the computer to automatically

detect and setup computer ISA peripherals, such asa modem or sound card.

Applications

Using the PnP technology, an end-user would have the

capability of connecting a device and not having to

configure the device using jumpers or dip switches.


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Block Diagram


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Bus width 32bit

Compatible with 8 bit ISA, 16 bit ISA, 32 bit EISA

Pins 98 + 100 inlay

Vcc +5 V, −5 V, +12 V, −12 V

Clock 8.33 MHz

Theoretical data rate (32 bit) about 33MB /s (8.33 MHz × 4bytes)

Usable data rate (32 bit) about 20 MB/s

Features


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Advantages• ISA Compatibility: ISA cards will work in EISA slots.

• 32 Bit Bus Width: Like MCA, the bus was expanded to 32 bits.

• Bus Mastering: The EISA bus supports bus asterin! adapters "or !reater

e""icienc#, includin! proper bus arbitration.

• Plug and Play: EISA autoaticall# con"i!ures adapter cards, siilar tothe $lu! and $la# standards o" odern s#stes

Disadvantages

It never became widely used .

It is no longer found in computers today.


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• Stands for "VESA Local Bus." (VESA stands for "Video Electronics

Standards Association").

• The VLB, or VL-bus is a hardware interface on the computer's

motherboard that is attached to an expansion slot.

• By connecting a video expansion card to the VLB, you can add extragraphics capabilities to your computer.

• The interface supports 32-bit data flow at up to 50 MHz.

• Though the VLB architecture was popular in the early 1990s, it hassince been replaced by the newer and faster, but still three-lettered,

ISA, PCI, and AGP slots.

VESA (Video Electronics Standard Association)


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Year created 1992

Created by VESA

Superseded by PCI (1993)

Width in bits 32

Number of devices 3

Speed 33 MHz

Style Parallel

Hotplugging interface no

External interface no


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Features

Bus width 32 bitsCompatible with 8 bit ISA, 16 bit ISA, VLB

Pins 112

Vcc +5 V

Clock

486SX-25: 25 MHz486DX2-50: 25 MHz

486DX-33: 33 MHz

486DX2-66: 33 MHz

486DX4-100: 33 MHz

486DX-40: 40 MHz486DX2-80: 40 MHz

486DX4-120: 40 MHz

5x86@133 MHz: 33 MHz

5x86@160 MHz: 40 MHz

486DX-50: 50 MHz

http://en.wikipedia.org/wiki/Pinhttp://en.wikipedia.org/wiki/Vcchttp://en.wikipedia.org/wiki/Vcchttp://en.wikipedia.org/wiki/Pin


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Advantages

• VLB video cards provide, in general,much better performance than

ISA cards.

• This is primarily due to the fact that the 32-bit local bus used by VLBcards allows for several times more data throughput between the card

and the processor than ISA allows.• VLB has however had its own share of problems. In particular, VLB

video cards may cause reliability problems in motherboards running at

40 or 50 MHz .• Many VLB cards are very good performers, but are hampered by their

general age, along with that of the motherboards they run in; most are

at least four years old and new development of better and faster

chipsets is entirely in the PCI world now.

• Still, despite the fact that VLB is older than PCI, it can provide quiteacceptable performance (although probably fewer features and less

video memory).• VLB is much closer to PCI than it is to ISA. Any system that will

support VLB should be using it for the video card .• The performance improvement over ISA is substantial in most cases.


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Disadvantages

• 80486 dependence. The VESA Local Bus relied heavily on the Intel

80486 CPU's memory bus design.

• Limited number of slots available. Most PCs that used VESA Local

Bus had only one or two VLB capable ISA slots from the 5 or 6 available

(thus 4 ISA slots generally were just that, ISA only).

• Reliability problems. The strict electrical limitations on the bus also

reduced any "safety margin" available - negatively influencing reliability.

• Limited scalability. As bus speeds of 486 systems increased, VLB

stability became increasingly difficult to manage.

• Installation woes. The length of the slot and number of pins made VLB

cards notoriously difficult to install and remove.


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• PCI (Peripheral Component Interconnect) is an interconnection system

between a microprocessor and attached devices in which

expansion slots are spaced closely for high speed operation.

• Using PCI, a computer can support both new PCI cards whilecontinuing to support Industry Standard Architecture (ISA) expansion

cards, an older standard

PCI (Peripheral Component

Interconnect)


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Year created July 1993

Created by Intel

Supersedes ISA,EISA,MCA, VLB

Superseded by PCI Express (2004)

Width in bits 32 or 64

Speed 133MB /s (32-bit at 33 MHz – the

standard configuration)

266 MB/s (32-bit at 66 MHz or 64-bit

at 33 MHz)

533 MB/s (64-bit at 66 MHz)

Style Parallel

Hotplugging interface Optional

Features


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Block Diagram


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PCI (Peripheral Component Interconnect) is an interconnection system

between a microprocessor and attached devices in which expansion slotsare spaced closely for high speed operation.

Using PCI, a computer can support both new PCI cards while continuing to

support Industry Standard Architecture (ISA) expansion cards, an older

standard

For image processing, PCI lets applications stream live video to a display or

system memory, virtually eliminating the need for costly onboard memory.

For example, a video camera that sends 30 frames/s produces data streams

of 10 to 40 MB/s, far outpacing ISA’s capacity of 3 to 5 MB/s of continuous

data.


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Advantages

• very high speed.

• Plug & Play.

• Dominant board-level bus

Disadvantages

• Incompatible with oldersystems

• Can cost more


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Year created 2004

Created by •Intel•Dell

•HP

•IBM

Supersedes • AGP

•PCI

•PCI-X

Width in bits 1–32

Number of devices One device each on each endpoint of each

connection. PCI Express switches can create

multiple endpoints out of one endpoint to

allow sharing one endpoint with multiple

devices.

Style Serial

Hotplugging interface Yes, ifExpress Card,Mobile PCI Express

Module or XQD card

PCI-E


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Year created 1998

Created by IBM,HP, andCompaq

Superseded by PCI Express (2004)

Width in bits 64

Speed 1064 MB/s

Style Parallel

Hotplugging interface yes

PCI-X


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PARAMETERS PCI PCI-E PCI-X

Stands For Peripheral

Component

Interconnect

Peripheral

Component

Interconnect

Express

Peripheral

Component

Interconnect

Extended

Format 32-Bit OR

64-Bit

32-Bit 64-Bit

Style Parallel Serial Parallel

Hot Plugging

Interface

Optional Optional Required

Speed 133MBps 250MBps-

31.51GBps

1084MBps


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• The pc provides fully-programmable asynchronouscommunication capabilities , through two standard EIA RS-

232C connections to the Multi I/O card.

• This adapter features programmable baud rates from 50 to

9600 baud, a fully programmable interrupt system andvariable character lengths(5,6,7, or 8-bit characters).

• In addition, the adapter adds and removes start, stop and

parity bits, has false start-bit detection, line-break detection

and generation, and possess build-in diagnostics

capabilities.

RS-232(Recommended Standard)


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1.Communication:asynchronous full duplex seriesdata communication.

2.Speeds:150 bps to 19.2 kbps

3.Length: typ. 75 ft (@ 9600 bps)

min. 50ft (@ 19.2 bps)

max. 2000 ft (@ 150 bps)4.Voltage levels : Logic 0 -> +3 V to +25 V (typ.+12V)

Logic 1 -> -3 V to -25 V (typ. -12V)

5.Cable : Multi-cored shielded.

Features


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Advantages

• Electrical signal characteristics such as voltage

levels, signaling rate, timing and slew-rate of signals,voltage withstand level, short-circuit behavior, and

maximum load capacitance.

• Interface mechanical characteristics, pluggable connectors

and pin identification.

• Functions of each circuit in the interface connector.

• Standard subsets of interface circuits for selected telecomapplications


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Features

• The Personal Computer works as a Host.

• The Low-powered devices can draw their power from the host via USB. If wehave to connect a hih power device then we have to use e!ternal adapter.

•USB ca"le has two twisted pairs of wires. #ne for the data transfer and the

other for power transfer.

•$e can connect ma!imum %&' USB devices to a host via USB hu"s.

•USB devices are hot swappa"le That means we do not have to turn o)* #nor restart our computer when connectin or disconnectin a USB device.

•$hen the computer enters in power savin mode* USB devices also put tosleep "+ the computer.


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Diagram


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Advantages

• Much moreresistant to scratches unlike CD

Roms and floppies.

• Much moreconvenient, will work with almost

any computer as long as there is a flash drive.

• Greatstorage space.

• It's small size is convenient for carrying, and

takes little space.

• One can purchase a USB that more reflects

them through itscolors and design.


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Disadvantages

• It's small size also means it can be lost easily and/orforgotten.

• Its life span can beshort, about several hundred

thousand cycles.

• As the device ages thespeed of writing processgraduallyslows.• Only a few USB flash drives are equipped with

awrite-protect mechanism,meaning those that don't

have the protection could be contaminated by what

ever virus the computer it was connected to has.• If inappropriately removed from the USB drive

without being ejected, it become damaged or lose the

data saved to it.


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Application

• Today, SuperSpeed USB 3.0 provides the highest standard in USBperformance—up to 10 times faster than High-Speed USB 2.0, with

a design data rate of five Gbps. In addition, Super Speed USB

dramatically reduces the power necessary to transfer large amounts

of data.

• This latest version of USB retains full backward compatibility with

previous generations, so existing platforms and devices will plug-

and-play equally well with newer platforms and devices that support

Super Speed USB.

• Portable devices such as handhelds, cell phones, and digital cameras

that connect to PCs as USB peripherals benefit from having

additional capabilities to connect to other USB devices directly

using USB On-The-Go (OTG) technology.


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Block Diagram


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Features

• A simple common plug-in serial connector on the back of your

computer and on many different types of peripheral devices

• A thin serial cable rather than the thicker parallel cable you now

use to your printer, for example

• A very high-speed rate of data transfer that will accommodatemultimedia applications (100 and 200 megabits per second today;

with much higher rates later)

• Hot-plug and plug and play capability without disrupting your

computer

• The ability to chain devices together in a number of different ways

without terminators or complicated set-up requirements


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• Simple cabling.

• Lower cost compared to parallel and Camera Link

standards.

• Does not require camera files.

• Supports a variety of frame rates and image sizes.

• Supports multiple cameras on a single frame grabber.

• Available on PCMCIA cards for laptop us.

• Does not require National Instruments hardware.

Advantages


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Disadvantages

• Slower data transfer rate - up to 400 Mbps for 1394a, upto 800Mbps for 1394b (dependent on camera, IEEE 1394

interface hardware, and operating system support).

• No onboard memory for saving images.

• Less triggering support.

• Difficult to synchronize with other devices.

A li ti


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Application

• FireWire helped fuel a revolution for digital content creators, and was awarded

a 2001 Primetime Emmy Engineering Award by the Academy of Television

Arts & Sciences for its contribution.

• Due to its high bandwidth and support of both isochronous and asynchronous

data delivery, FireWire has found a very successful place in both the computer

and consumer electronics industries.

• Whether connecting game consoles, personal video recorders, home stereoequipment, digital TVs, hard drives, CD/DVD-RW drives, printers, scanners,

tape drives or other digital hardware equipment, FireWire is well-suited to

handle all these various requirements.

• With the advent of the new FireWire 800 standard, the revolution created by

the original will only grow.

• For those working with digital video, the new standard will enable new

bandwidth-intensive applications, such as multiple-stream, uncompressed,

standard-definition video.

SCSI(S llC t S t It f )


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SCSI (Small Computer System Interface)

The Small Computer System Interface (SCSI) is a

set of parallel interface standards developed by the American National Standards Institute (ANSI) for

attaching printers, disk drives, scanners and other

peripherals to computers. SCSI (pronounced

"skuzzy") is supported by all major operatingsystems.

Symbol


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Features

• The first version (SCSI-1), adopted by ANSI in 1986, was an 8-bit versionwith a 5 MBps transfer speed that allowed up to eight devices to be connected

with a maximum cable length of six meters.

• The latest version, 16-bit Ultra-640 (Fast-320) SCSI, was introduced in 2003

and has a 640 MBps transfer speed, connecting up to 16 devices with a 12

meter cable length. Other versions include:

• SCSI-2: 8-bit bus, six meter cable length, 5-10 MBps; connects 8 or 16

devices. 50-pin connector


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Block Diagram


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Advantages

1. SCSI can handle a wide variety of devices: hard drives, scanners, plotters, CD

drives, and the list goes on.

2. A SCSI controller can communicate with up to 7 or 15 devices depending on theversion. I am sure work is being done to add more.

3. It is often easier to install and setup a SCSI device than with many other device

interfaces. (This comment is not limited to the SCSI vs. IDE issue. See Advantage #1

for the scope of what I mean by "device." I also say it is "often easier," not "universally

easier.")

4. SCSI controllers and devices are intelligent, they have microcontrollers, if not fullblown processors, inside them. They do not require software-base controller drivers

like some Windows devices, putting less load on the CPU.

5. SCSI has proven itself to be a good platform for moving and storing large amounts

of data. Recent developments with SCSI have focused on exploiting this feature even

further.

6. Newer SCSI devices and controllers are supposed to be backward compatible witholder SCSI devices and controllers. (from my own personal experience, this is about

95% true)

7. Recent SCSI controller and devices currently offer the highest through-put for any

peripheral connection scheme currently available.

8. SCSI drives are, on the whole, more reliable than ATA/IDE drives


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A li ti


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Application

• SCSI is used to connect peripherals to an computer.

• It allows you to connect hard disks, tape devices, CD-

ROMs, CD-R units, DVD, scanners, printers and many

other devices.

• SCSI is in opposite to IDE/ATA very flexible.

• Today SCSI is most often used servers and other

computers which require very good performance.

• IDE/ATA is more popular due to the fact that IDE/ATA

devices tend to be cheaper.

C (P lllP )


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Centronics(Parallel Port)

The Centronics interface is a standard input/output (I/O) interface designed

in the 1970s for connecting printers and other devices. It was developed by

the Centronics printer company which is now defunct. The Centronicsinterface, also known as a Parallel Port, became the standard means of

connecting printers to personal computers for decades.

The technology that the Centronics interface developed into included a

number of incarnations of the Parallel interface including the ECP

(Extended Capabilities Parallel) and EPP (Enhanced Parallel Port) versions.The technology required a 25 way connector of which up to 17 wires were

used in the specification and bi-directional communications became possible

in the enhanced versions like ECP and EPP.

Today, the Centronics interface has been largely replaced by the universal

serial bus (USB). For the most part, many manufactures have entirely

omitted the parallel interface. However, a USB-to-parallel port adapter is

available for PCs without a parallel port. These can be used for parallel

printers and other peripheral devices that have a parallel interface.


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PARALLEL SERIAL

A parallel bus is one where each bit

has its own copper wire.

A parallel bus is one where each bit

has its own copper wire.

There is usually a strobe line that says

when the data bits are valid.

There is usually some framing

information to identify the start of a

frame of data, such as a long gap.

Examples of parallel bus: PCI, IDE,

SCSI

• Examples of parallel bus: PCI, IDE,

SCSI

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