2Learning Outcomes Define the term bus Explain the different bus characteristicsCalculate bus throughput in bps and MB/sExplain BSB, and FSBExplain Double Data Rate, Quad Data Rate, and HyperTransportDefine the term expansion busExplain the different expansion bus typesCompare VESA versus PCICompare PCI versus AGPDescribe different ports (Serial, Parallel, USB, FireWire, IDE, EIDE, SCSI and SATA)Discuss RAID, Interrupt, and PnP
3BusA collection of wires/tracks that transfer data or power between computer components, typically controlled by a device driver softwareinternalexternalcomputer to computerEvery component in a computer connects to a bus - even components such as the VDU or printer connect to a bus in some way
4Bus characteristics Clock speed Width Bus performance Control signals Logical and physical connectionInternal and externalSerial and parallel
5Clock speed number of times a bit is sent along the bus measures how quickly bits move along a busClock speed is simply the number of times that a bit (or a group of bits) is sent along the bus. In practical terms, it is a measure of how quickly each bit moves along a bus.
6Widthnumber of data bits that can be sent along the bus at once (i.e. 8, 16, 32, 64bits)The bus width is the number of data bits that can be sent along the bus at once (but not control bits). If 8 bits can be sent along the bus at the same time, then the bus width is 8 bits. A bus whose width is 16 bits can carry 16 bits at the same time. Typical values are 8, 16, 32 and 64 bits.
7Bus performance Bus throughput Bus throughput calculation number of bytes of data that can be transferred via the bus in one secondBus throughput calculationbus clock speed * bus width = bus throughputBus throughput is the number of bytes of data that can be transferred via the bus in one second. Throughput is usually given in megabits per second (Mb/s). Bus throughput can be calculated using the formula:[throughput] = [bus width] × [clock speed]For example, if the bus width is 16 bits and the clock speed is 8MHz, then the throughput isthroughput = (16 bits) × (8MHz) = 128Mb/s
8Control signals which component the data is for where blocks of data start and endany other information related to the data being transferredA bus does not just carry data. It also carries control signals that tell components what to do with the data. Control signals provide information such as:Which component the data is for.Where blocks of data start and end.And any other information related to the data being transmitted.
9Logical and physical connection Logical connectionOne-to-many (several devices sharing the same set of wires) or point-to-point connectionPhysical connectionEach bus defines its set of connectors to physically plug devices, cards or cables together
10Internal and externalInternal bus connects all the internal components of a computer to the motherboardalso referred to as a local / Motherboard bus, because they are intended to connect to local devicesExternal bus connects external peripherals to the motherboard
11Serial and parallel Serial buses Parallel buses carry data in bit-serial formParallel busescarry data words striped across multiple wiresproblem: crosstalk across multiple wires
17Expansion busA collection of wires and protocols that allows the expansion of a computer by inserting printed circuit boards (expansion boards)
18Expansion bus typesPC BusISAMCAEISAVESAPCIAGPPCI Express
19PC Bus 1981 Developed for the original IBM PC Used on 8088 and 8086 motherboardswidth: 8bspeed: 4.77MHzthroughput:38.16Mbps4.77MB/s
20ISA Industry Standard Architecture 1984 twice the width of PC bus PC bus is backwards compatible with ISAlocal bus for the Intel 386 CPUStill today, some motherboards that support Pentium 4 processors have an ISA expansion busUsed on 286, 386, 486, Pentium and some Pentium 4 motherboardswidth: 16bspeed: 8MHzthroughput:128Mbps16MB/s
21MCA Micro-Channel Architecture 1987 IBM introduced MCA to replace ISA, but it never became popular and was soon discontinuedTwice the width of ISA but not compatible with the ISA or PC busUsed on 386 and 486 motherboardswidth: 32bspeed: 10MHz or 16MHzthroughput:320Mbps - 512Mbps40MB/s - 64MB/s
22EISA Extended Industry Standard Architecture 1988 Used on 486 motherboardswidth: 32bspeed: 8.33MHzthroughput:____266.56Mb/s______________33.32__ MB/s
23VESA Video Electronics Standards Association aka VESA Local Bus (VLB) 1992Twice the width of ISAISA and PC bus are backwards compatible with VESAUsed on 486 motherboardswidth: 32bspeed: 66MHz (maximum)throughput:___2112_______ Mbps___264_______ MB/s
24PCI 1.0 Peripheral Components Interconnect 1992 (1995 with Windows 95) Supports Plug and Play (PnP)Used on Pentium motherboardsTransfers data only on one edge of the clock signalwidth: 32bspeed: 33MHz (maximum)throughput:___1056_______ Mbps___132____ MB/s
25PCI 2.0 PCI 1.0 is backwards compatible faster and wider than PCI 1.0 width: 64bspeed: 66MHz (maximum)throughput:_____4224_____ Mbps_____528_____ MB/s
27AGP (1 of 2) Accelerated Graphics Port 1997 Intel bus specification providing faster memory access than PCIGreatly speeds Virtual Reality (VR) and 3D (Dimensional) rendering and texture mapping than PCIDeveloped only for video cardsUsed on Pentium II motherboardsIn its lowest speed mode the throughput is twice as fast as PCI, plus the benefits of not having to share the bandwidthTransfers data on two edges of the clock signal
28AGP (2 of 2) width: 32b speed: 66MHz throughput: 2,112Mbps264MB/sAvailable in four speeds (four specifications), the clock is doubled each time:x1 264MB/sx2 528MB/sx4 _1,056____ MB/sx8 __2,112___ MB/s
29PCI versus AGP Pipelined requests PCI AGP Non-pipelined requests Address/data multiplexedAddress/data de-multiplexedPeak throughput in 32b is 132MB/sPeak throughput in 32b is 264MB/sMulti-target, multi-masterSingle-target, single-masterLink to entire systemMemory read/write only, no other input/output operationsNo priority queuesHigh/low priority queues
31PCI Express (1 of 2) Peripheral Components Interconnect Express (PCIe) 2004Initially named 3GIO (Third Generation Input/Output)high speed connectionUsed on Pentium 4 motherboardsUses a packetised protocol (8bit/10bit encoding)Starting freqency 2.5GHZ, go up to 10 GHZHot plug and hot swappable capabilityPower management capabilities
32PCI Express (2 of 2) Uses point-to-point connections known as lanes Each lane on the bus is capable of transferring data in full duplex over two pair of differentially signaled wires called a .Each lane allows 250 MBps throughput in each direction. Design allows for scalling from 1 to 2, 4, 8, 16 and 32 lane (x16 bus totals 32 lanes)Four bus types: x1, x4, x8, x16x1 bus throughput is 250MB/s * 2 = 500MB/sx4 bus throughput is 1GB/s * 2 = 2GB/sx8 bus throughput is 2GB/s * 2 = 4GB/sx16 bus throughput is 4GB/s * 2 = 8GB/s
33PCI Express 2.0 Released 15 January 2007 Doubles the bus standard bandwidth of previous versioni.e. x16 bus throughput at 8GB/s * 2 = 16GB/sis backwards compatibleFeatures improvements to the point-to-point data transfer protocol and its software architectureIntel is expected to release its first chipsets supporting PCIe 2.0 in the second quarter of 2007 with its ‘Bearlake’ familyAMD starts supporting PCIe 2.0 from its RD700 chipset seriesNVIDIA has revealed that the MCP72 will be their first PCIe 2.0 equipped chipset
38Serial 1 copper wire slower 1 bit at a time Serial protocol faster, fewer electrical connections and inherently has no timing skew or crosstalk
39Parallel 8 copper wires faster 8 bits at a time Slower in comparison to Serial packetized protocol
40USB Universal Serial Bus 127 devices, daisy chained bus designed to eliminate cable clutterhub is very important unit, each device can hold another hub for other devices (PC to PC)4 wire cable: 2 wires supply power for devices, other 2 wires used to send data and commandsPnP and hot swappableinternal and externalIn expensive cable which can reach up to 5 meters long (USB hubs can be daisy chained up to 25m)USB 1.0 = 1.5Mbps (keyboard mouse), 12Mbps (printer, monitors , etc)USB 2.0 = 480MbpsUSB 1.0 is backwards compatible with USB 2.0
41Hot swapping and hot plugging are terms used to separately describe the functions of replacing system components without shutting down the system. Hot swapping describes replacing components without significant interruption to the system, while hot plugging describes the addition of components that would expand the system without significant interruption to the operation of the system.For hot swapping once the appropriate software is installed on the computer, a user can plug and unplug the component without rebooting. A well-known example of this functionality is the Universal Serial Bus (USB) that allows users to add or remove peripheral components such as a mouse, keyboard, or printer.
42FireWirei.Link or IEEE 1394different versions of FireWire (FireWire 400, FireWire 800)up to 800Mbps4.5m cable length16 cables can be daisy chained up to 72 meters longserial63 deviceshot pluginternal and external4-pin (digital camera) and 6-pin FireWire (PC)power provided
43IDE Intelligent / Integrated Device Electronics Parallel ATA (Advanced Technology Attachment)cheap devices and controllersmaximum of 2 drivesonly supports hard drives maximum of 528MB capacityeasy to install and setupslowinternal drives onlyno power provided
44EIDE Enhanced IDE Parallel ATA used on Pentiums cheap drives and controllersmaximum of 2 drives for each of the 2 controllers (4 drives)300GB storage capacitiesHDD, CD, DVD, Zip driveseasy to install and setup40 cable pins ( wires)internal drives onlyUltra/ATA 133 (133MB/s)cable 40cm longbulky, inflexible, fragile and too shortnot hot swappable4 pin power connectorno power provided
46EIDE drivesConfigure jumpers on EIDE devices (1 hard disk drive and 1 CD-ROM drive)
47SATA Serial ATA (internal) up to 1 meter cable length eSATA (external) up to 2 meter cable length7 cable pins (4-7 wires)one serial drive per portpoint-to-point connectionconnectors are 8mm widecable thinner and more flexible, provides better airflowconnectors are more compacthot-plug capability1.5Gbps (150MB/s *8 = 1200 = 1.2Gbps + overheads = 1.5Gbps), 3Gbps (300MB/s), 6Gbps (600MB/s)15-pin power connectorsupports 8B/10B encodingno power provided
49SCSI Small Computer Systems Interface use on servers and non-Intel PC expensive drives and controllerssupports 7-15 devicesall types of drives (i.e. hard disks, scanners)hard to install and setupfast for serversexternal drivesup to 12 meter cable length (Ultra-320 SCSI = 320MB/s)must use terminatorno power provided
51A SCSI ChainThe advantage of SCSI is that several peripherals can be daisy chained to one host adapter, using only one slot in the bus.
52RAID Redundant Array of Independent / Inexpensive Disks Multiple disks accessed in parallel will give greater throughput than a single diskRedundant data on multiple disks provides fault toleranceused in servers or main frames (although can be commonly setup on desktop PCs)provides higher reliability and/or faster access/performance depending on RAID typedrives in a RAID system are hot swappable for servers and mainframesRAID appears to the OS as one single logical hard disk6 standards (RAID 0 to RAID 5) (RAID 1 = mirroring)although can get different combinations of RAID (RAID 10, RAID 53)
55Interrupt A signal informing a program than an event has occurred IRQ (Interrupt Request Queue)each device or expansion card has its own unique IRQ, to prevent hardware conflict
56Interrupt characteristics Interrupts can come from a variety of sourcesThe PC supports 256 (0-255) types of interrupts: 15 are hardware interrupts and 241 are software interrupts
575 Interrupt classifications Highest to lowestReset button / power buttonInternal CPU error (overflow)NMI (Non-Maskable Interrupt) - parity error or power fail detectSoftware INT instruction - interrupt signals initiated by programsExternal hardware interrupts - IRQ, alt-ctrl-del, keystroke, printer call
58Plug and PlayA plug and play system is one that can automatically find and configure all of the hardware devices (also called components) in a system.
59Before Plug and PlayBefore plug and play, any device had to be configured manually. This meant:Finding the resources that were available;Finding out what resources are supported by the device;Manually configuring the device to use these resources. This meant fiddling with small switches, called jumpers, on the card itself.This made adding a new device difficult.
60With Plug and PlayA plug and play configures these resources automatically. This means that you can simply add a device, and the operating system will handle all of the configuration for you.To use plug and play:Your devices must be able to work with plug and play;Your computer must be able to work with plug and play. Your motherboard and BIOS will have to support plug and play, as they are used in the plug and play processYour operating system, such as Windows 95 or Windows 98, must be able to work with plug and play. They will control the plug and play process.
61Plug and PlayPnPautomatic selection of IRQs (and other system resources)previously IRQs were manually selected by jumpers on expansion cardsthe user had to select an unused IRQ to prevent interrupt conflictto use PnP: require a PnP expansion card, PnP BIOS, PnP OS and PnP motherboard support