A.S. 2/4/2014

5. Data Ports

Prof. Dr. M. H. Assal

Introduction to Computer

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Data Ports The interfaces for attaching external devices to a

computer or The doors through which information enters and

leaves a computer system. and leaves a computer system.o PS/2 ports (Mouse, Keyboard)o Serial ports (Mouse, modems, printers) 150 kbpso Parallel ports (printers, scanners, external data drives) 1.2

mbpso SCSI ports – Small Computer Systems Interface

(many internal and external devices) up to 320 mbpso USB ports - Universal Serial Bus

(nearly everything) 1.5 - 12 - 480 - 4000 mbpso Firewire Connections (imaging devices – digital

camcorders, scanners) 100-800 mbps

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Data Ports

PS/2 Ports Serial Port

Parallel Port

USB

SCSI

Firewire Ports

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Data Port Features Fast Reliable Flexible Inexpensive Power-conserving Supported by the operating system

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Parallel Port Commonly known as the printer port 25 pin D-Type connector It has 12 digital output pins, 5 digital input pins Pins operate at the TTL voltage level i.e. 0 – 5V Port identified by a base address in the computer

I/O memory space

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Serial Port 9 pin D-Type connector Pins operate at -25 to +25 voltage levels Data transmitted as a bit sequence Known as the EIA RS232C port or simply

RS232 Maximum date rate of 19,600 bps

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Serial Port vs. Parallel Port

Serial cables can be much longer than Parallel cables

Serial suited for wireless transmission

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Universal Serial Bus Universal Serial Bus (USB) was designed in mid-

1990s to standardize the connection of computer peripherals to computers.

It has become commonplace on other devices (such as smartphones, PDAs and video game consoles).

USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports.

USB is a likely solution any time you want to use a computer to communicate with devices outside the computer

Device, male connector Computer, female connector Hub

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Universal Serial Bus

Interface # of De-vices

(maximum)

Length(max feet)

Speed(max. bps)

Typical Use

USB 127 16 (or up to96 ft. with 5

hubs)

Ver. 1.0 1.5 M (nearly everything)Mouse,

Keyboard, Hard Drives, Mass Stor-

age, Network Adapters, Audio, Camcorders

Ver. 1.1 12 M

Ver. 2.0 480 M

Ver. 3.0 5 G

RS-232 2 50-100 20 K (115K with

somehardware)

Modems, MouseBar-Code ReadersInstrumentation

Parallel (Printer) Port

2 10–308 M

PrintersScanners

IEEE-1394 (FireWire)

64 15 IEEE-1394a

400 M

Digital Video (Cam-corders)

Old iPod & iPhoneMass StorageIEEE-

1394b 3.2 G

Comparison

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Universal Serial Bus USB Features

Flexible Ease of use was a major design goal for USB, and the result is an interface that’s a pleasure to use for many reasons: Windows automatically detects the peripheral and loads the appropriate software driver.There’s no need to locate and run a setup program or restart the system before using the peripheral.

One interface for many devices. USB is versatile enough to be usable with many kinds of peripherals. Instead of having a different connector type and supporting hardware for each peripheral, one interface serves many.

SpeedUSB supports three bus speeds: high speed data transfer.

ReliabilityThe reliability of USB results from both the hardware design and the data-transfer protocols.

Low Cost

Low Power Consumption

Universal Serial BusIt’s Not Perfect

Lack of Support for Legacy HardwareOlder (“legacy”) computers and peripherals don’t have USB ports. If you want to connect a non-USB peripheral to a USB port, a solution is a converter that translates between USB and the older interface .

Distance LimitsUSB was designed as a desktop bus, with the expectation that peripherals would be relatively close at hand. A cable segment can be as long as 5 meters. You can increase the length of a USB link to as much as 30 meters by using cables that link five hubs and a device, using 6 cable segments of 5 meters each.

Peer to Peer CommunicationsUSB can’t talk to each other directly. All communications are to or from the host computer. Other interfaces, such as IEEE-1394, allow direct peripheral- to-peripheral communications.

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Universal Serial Bus

USB 2.0 A big step in USB’s evolution was version 2.0.

Support for much faster transfers.

a 40-times increase was found to be feasible, for a bus speed of 480 Megabits per second.

USB 2.0 is backwards compatible with USB 1.1.

Version 2.0 peripherals can use the same connectors and cables as 1.x peripherals.

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Universal Serial BusUSB 3.0

Released in November 2008 Also referred to as SuperSpeed USB Speeds 10x faster than 2.0 (5 Gbps in controlled test

environment) Extensible – Designed to scale > 25Gbps Optimized power efficiency Backward compatible with USB 2.0

o USB 2.0 device will work with USB 3.0 hosto USB 3.0 device will work with USB 2.0 host

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Universal Serial Bus

Added pins for SuperSpeed USB signals.

Compatibility for USB 2.0 connectors.

Different shapes of connectors are provided to support the compatibility with current (USB 1 & 2) devices.

USB 3.0 Connectors

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USB vs. Firewire (IEEE-1394)

USB Firewire

Multiple devices support

Single host can communicate with many peripherals/devices

127 64

Peer to Peer No Peer-to-Peer support

Support Peer-to-Peer model, where peripherals can communicate with each other directly

Cost Relatively Cheap Expensive

THANK YOU