IT Systems In and Out EN230-1 Justin Champion C208 –

IT Systems Contents What is I/O Motherboards Types of I/O

IT Systems I/O ?? Stands for Input/Output A large number of devices allow us to send information into the processor and receive it afterwards Hard Disks Ram CD-Writers Keyboards Printers Monitors Etc, etc

IT Systems A number of standards are defined for I/O Standards are required so that any device which meets that standard can communicate with any other device USB SCSI RAM (Discussed last week) IDE Serial Parallel FireWire

IT Systems These standards are being used to get information to the processor Once at the processor this information can then be acted upon. To allow all of these devices to communicate with the processor they must be connected together The motherboard allows all of the devices to connect together for communications

IT Systems Motherboard This is a integrated circuit which allows circuits to be developed between all of the devices attached

IT Systems Bus? The bus is the way that data is moved around the motherboard Each part communicates with the System bus

IT Systems System Bus consists of Data Bus The data that is transferred at once The bigger the more information which can be transferred in one cycle Control Bus Carries control signal so that all devices now the current operation state Address Bus Indicates where the data is intended for The bigger the more device that can be attached

IT Systems Data Bus The data bus for efficiency should be able to carry the maximum amount of data the processor can deal with Bit address bus, maximum 16Mb of memory & Address Bus, 4 Gb of memory Intel Itanium - 64 bit 64 Address Bus, Sixteen exabytes ???

IT Systems Storage Memory Sizes Bit – 0 or 1 Byte – 8 * bits KiloByte – 1024 * Bytes MegaByte * Kilobytes GigaByte * MegaByte TeraByte * GigaByte Petayte * TeraByte Exabyte * PetaByte ZettaByte * ExaByte YottaByte * ZetaByte or bytes

IT Systems BIOS Basic Input/Output System (BIOS) This is a piece of software which is written into the motherboard of your PC It has just the knowledge to carry out a number of actions before handing over to the operating system Power on Self Test (POST) Checks all components are working correctly Loads controls for Keyboard Disk drives (hard disk and floppy) Serial communications VGA basic display

IT Systems Hard Disc The primary permanent storage area for a PC A hard disc operates by changing the magnetic properties of the surface of a disc The magnetic poles are changed in one bit to indicate either a 0 or a 1 A arm is then moved across the platter which contains the bits to read back or write to a specific part of the hard disc The platter is made up of sectors and tracks These are then made up into clusters The size of the cluster depends on the OS computer.howstuffworks.com/hard-disk3.htmcomputer.howstuffworks.com/hard-disk3.htm, 2003

IT Systems Hard Disc Cluster When you write data to a cluster the entire cluster is used Even if the file does not fill the cluster This can be seen in this picture from win2000 File size and size on disc

IDE Integrated Drive Electronics (IDE) Common speeds are UDMA33 = 33 Mbps UDMA100 = 100 Mbps IDE interfaces Maximum of 2 devices per controller These drives are cheap and mass produced Maximum cable length of 48cm Higher system costs as the controller requires CPU time Are useful all uses with the exception of very intensive disk usage

SCSI Small Computer System Interface (SCSI) Commonly considered to be the faster drives Fastest specification is Ultra 3 SCSI 240 Mbps, but this is not widely available Most SCSI drives are similar in speed to IDE Interface Can cope with 8 devices attached to it Can buffer instruction sent to the device Very low CPU overhead for instructions typically 5% Maximum cable length of 12 Metres These drives are expensive! Mostly used today on high end servers, where a number of drives needs to be connected at any time

Serial Is the sending of one bit of data at a time This gives the advantage of only one cable being required for transmission They are able to send duplex data Duplex indicates that data can be sent and received at the same time. This is carried out by transmitting on a different cable than receiving upon Pin 2 transmits data and pin 3 receives data Standard serial ports can received data at 115 Kbps (using the RS232 standard)

Serial 9 Pin serial port

Serial Traditional serial connection is through RS-232 and its successors Newer standards are available RS-442 Allows faster speeds and longer connection cables, 4000 ft at 100 Kbps or a maximum speed of 1.5 Mbps with a shorter cable RS-485 Allows up to 16 devices daisy chained together to communicate Similar speeds but this medium is shared like Ethernet

Serial Traditionally used for Modem communications Still widely used a lot of handheld devices use serial communications ports.

Serial Parallel – IEEE 1284 standards Unlike serial uses 8 wires at once This allows 1 byte at a time to sent over the cable Standard Parallel Port (SPP) 100 Kbps Enhanced Parallel Port (EPP) 500Kbps to 2 Mbps

Serial & Parallel Parallel devices current uses Printers External Zip drives External CD drives Data Transfers

Universal Serial Bus (USB) Standards 1.0 – 12 Mbps 2.0 – 480 Mbps Maximum of 127 devices daisy chained together All share a single interrupt (IRQ) These devices can supply a small amount of electricity 500 Milliamps at 5 volts Now available for all operating systems Including Linux

Universal Serial Bus (USB) Devices are Hot swappable Can be put to sleep Data can be transferred in different methods Interrupt based Small amounts of data to be transferred Bulk Large amounts of data like a scanner Isochronous Continuous data transfer like a web cam Data transfer rates are guaranteed for the devices

Firewire IEEE-1394 High-speed serial bus, originally called Firewire, developed by Apple in 1995 I-link used by Sony Offers data rates of Mbps Allows a maximum 63 nodes to be connected A maximum of 72 metres of cable between the host and the device (using a daisy chain) The cabling can provide the power to the device if required 40 volts with 1.5 amps maximum Mainly used for digital video transfer where this throughput is required

IT Systems Summary of what we have discussed Motherboard Processor types I/O Types Hard disc USB Serial FireWire