1.  Prof. Dr. M. H. Assal A.S. 2/4/2014

2.  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 kbps o Parallel ports (printers, scanners, external data drives) 1.2 mbps o SCSI ports – Small Computer Systems Interface (many internal and external devices) up to 320 mbps o USB ports - Universal Serial Bus (nearly everything) 1.5 - 12 - 480 - 4000 mbps o Firewire Connections (imaging devices – digital camcorders, scanners) 100-800 mbps 2

3. PS/2 Ports Serial Port Parallel Port USB SCSI Firewire Ports 3

4.  Fast  Reliable  Flexible  Inexpensive  Power-conserving  Supported by the operating system 4

5.  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 5

6.  I/O Registers o Most PC’s have 378 Hex base address o 8 output pins are accessed via the DATA port (Base address) o 4 output pins are accessed via the CONTROL port (Base address + 2) o 5 input pins are accessed via the STATUS port (Base address +1) 6

7.  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 7

8.  Serial cables can be much longer than Parallel cables  Serial suited for wireless transmission 8

9.  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 9

10. Interface# of Devices (maximum) Length (max feet) Speed (max. bps) Typical Use USB12716 (or up to 96 ft. with 5 hubs) Ver. 1.0 1.5 M(nearly everything) Mouse, Keyboard, Hard Drives, Mass Storage, Network Adapters, Audio, Camcorders Ver. 1.1 12 M Ver. 2.0 480 M Ver. 3.0 5 G RS-232250-100 20 K (115K with some hardware) Modems, Mouse Bar-Code Readers Instrumentation Parallel (Printer) Port 210–30 8 M Printers Scanners IEEE-1394 (FireWire) 6415 IEEE-1394a 400 M Digital Video (Camcorders) Old iPod & iPhone Mass Storage IEEE-1394b 3.2 G Comparison 10

11. History  The main reason that new interfaces don’t come around very often is that existing interfaces have the irresistible pull of all of the existing peripherals that users don’t want to scrap.  Also, using an existing interface saves the time and expense of designing something new.  This is why the designers of the original IBM PC chose compatibility with the existing Centronics parallel interface and the RS-232 serial-port interface to speed up the design process and enable users to connect to printers and modems already on the market.  These interfaces proved serviceable for close to two decades.  But as computer power and the number of peripherals have increased, the older interfaces have became a bottleneck of slow communications, with limited options for expansion. 11

12. 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.  Speed USB supports three bus speeds: high speed data transfer.  Reliability The reliability of USB results from both the hardware design and the data-transfer protocols.  Low Cost  Low Power Consumption 12

13. It’s Not Perfect  Lack of Support for Legacy Hardware Older (“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 Limits USB 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 Communications USB 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. 13

14. 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. 14

15. USB 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 host o USB 3.0 device will work with USB 2.0 host 15

16.  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. 16 USB 3.0 Connectors

17.  Operates concurrently with USB 2.0 (Dual bus architecture) o Mechanically and electrically backward/forward compatible o Devices configured at fastest signaling rate o Hubs contain additional ports  Speed and power efficiency o Non polling reduces power consumption o Additional data lines included to increase speed o Efficiency of bandwidth – simultaneous communication between host and device o Dedicated in and out lines allow communication between host and device 17

18.  Physical Layer o Adopted from current industry specs o Signaling similar to existing high-speed buses PCI Express SATA 18

19.  All data transfers initiated by host  Hub can be up to 5 layers deep (127 devices)  Packets routed NOT broadcast  Hubs use “store and forward” procedures o Packets held by hub which are being directed to inactive port  Downstream packets use route string to navigate to device  Upstream always contains host as destination 19

20.  Host to Device o Sends PPT (Packet Pending Transfer) o When no PPT, device can reduce power usage  Use of packet suspension and asynchronous notifications  Hub inactivity timers 20

21.  WUSB is a form of USB technology that uses radio- frequency (RF).  WUSB technology is based on the WiMedia Ultra- Wideband common radio platform.  WUSB can provide transfer rates up to 480 Mbps (at 3 m) or 110 Mbps (at 10 m).  WUSB also allows for no more then 127 devices connected to a single host controller. 21

22.  The demand for increased connectivity without the clutter  Preserves the USB 2.0 layered architecture and communication flow o Point-to-point o Same transfer types, etc  WUSB interface still offers Plug and Play capability as well as hot swap hardward components  Maintains Backward Compatibility (1.0 and 2.0) 22

23. 23 USBFirewire Multiple devices support Single host can communicate with many peripherals/devices 12764 Peer to PeerNo Peer-to-Peer support Support Peer-to-Peer model, where peripherals can communicate with each other directly CostRelatively CheapExpensive

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