# Hardware Fundamentals

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Hardware Fundamentals
Week 4 - Lesson 1

Learning Outcomes Define the term bus
Explain the different bus characteristics Calculate bus throughput in bps and MB/s Explain BSB, and FSB Explain Double Data Rate, Quad Data Rate, and HyperTransport Define the term expansion bus Explain the different expansion bus types Compare VESA versus PCI Compare PCI versus AGP Describe different ports (Serial, Parallel, USB, FireWire, IDE, EIDE, SCSI and SATA) Discuss RAID, Interrupt, and PnP

Bus A collection of wires/tracks that transfer data or power between computer components, typically controlled by a device driver software internal external computer to computer Every component in a computer connects to a bus - even components such as the VDU or printer connect to a bus in some way

Bus characteristics Clock speed Width Bus performance Control signals
Logical and physical connection Internal and external Serial and parallel

Clock speed number of times a bit is sent along the bus
measures how quickly bits move along a bus Clock 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.

Width number 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.

Bus performance Bus throughput Bus throughput calculation
number of bytes of data that can be transferred via the bus in one second Bus throughput calculation bus clock speed * bus width = bus throughput Bus 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 is throughput = (16 bits) × (8MHz) = 128Mb/s

Control signals which component the data is for
where blocks of data start and end any other information related to the data being transferred A 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.

Logical and physical connection
Logical connection One-to-many (several devices sharing the same set of wires) or point-to-point connection Physical connection Each bus defines its set of connectors to physically plug devices, cards or cables together

Internal and external Internal bus connects all the internal components of a computer to the motherboard also referred to as a local / Motherboard bus, because they are intended to connect to local devices External bus connects external peripherals to the motherboard

Serial and parallel Serial buses Parallel buses
carry data in bit-serial form Parallel buses carry data words striped across multiple wires problem: crosstalk across multiple wires

BSB and FSB

BSB Back Side Bus The bus that connects the processor to the different levels of cache Found on the processor chip

FSB Front Side Bus The bus that connects the processor to the different hardware components found on the motherboard

Expansion bus

Expansion bus A collection of wires and protocols that allows the expansion of a computer by inserting printed circuit boards (expansion boards)

Expansion bus types PC Bus ISA MCA EISA VESA PCI AGP PCI Express

PC Bus 1981 Developed for the original IBM PC
Used on 8088 and 8086 motherboards width: 8b speed: 4.77MHz throughput: 38.16Mbps 4.77MB/s

ISA Industry Standard Architecture 1984 twice the width of PC bus
PC bus is backwards compatible with ISA local bus for the Intel 386 CPU Still today, some motherboards that support Pentium 4 processors have an ISA expansion bus Used on 286, 386, 486, Pentium and some Pentium 4 motherboards width: 16b speed: 8MHz throughput: 128Mbps 16MB/s

MCA Micro-Channel Architecture 1987
IBM introduced MCA to replace ISA, but it never became popular and was soon discontinued Twice the width of ISA but not compatible with the ISA or PC bus Used on 386 and 486 motherboards width: 32b speed: 10MHz or 16MHz throughput: 320Mbps - 512Mbps 40MB/s - 64MB/s

EISA Extended Industry Standard Architecture 1988
Used on 486 motherboards width: 32b speed: 8.33MHz throughput: ____266.56Mb/s______ ________33.32__ MB/s

VESA Video Electronics Standards Association aka VESA Local Bus (VLB)
1992 Twice the width of ISA ISA and PC bus are backwards compatible with VESA Used on 486 motherboards width: 32b speed: 66MHz (maximum) throughput: ___2112_______ Mbps ___264_______ MB/s

PCI 1.0 Peripheral Components Interconnect 1992 (1995 with Windows 95)
Supports Plug and Play (PnP) Used on Pentium motherboards Transfers data only on one edge of the clock signal width: 32b speed: 33MHz (maximum) throughput: ___1056_______ Mbps ___132____ MB/s

PCI 2.0 PCI 1.0 is backwards compatible faster and wider than PCI 1.0
width: 64b speed: 66MHz (maximum) throughput: _____4224_____ Mbps _____528_____ MB/s

VESA versus PCI

AGP (1 of 2) Accelerated Graphics Port 1997
Intel bus specification providing faster memory access than PCI Greatly speeds Virtual Reality (VR) and 3D (Dimensional) rendering and texture mapping than PCI Developed only for video cards Used on Pentium II motherboards In its lowest speed mode the throughput is twice as fast as PCI, plus the benefits of not having to share the bandwidth Transfers data on two edges of the clock signal

AGP (2 of 2) width: 32b speed: 66MHz throughput:
2,112Mbps 264MB/s Available in four speeds (four specifications), the clock is doubled each time: x1 264MB/s x2 528MB/s x4 _1,056____ MB/s x8 __2,112___ MB/s

PCI versus AGP Pipelined requests PCI AGP Non-pipelined requests
Address/data multiplexed Address/data de-multiplexed Peak throughput in 32b is 132MB/s Peak throughput in 32b is 264MB/s Multi-target, multi-master Single-target, single-master Link to entire system Memory read/write only, no other input/output operations No priority queues High/low priority queues

PCI Express (1 of 2) Peripheral Components Interconnect Express (PCIe)
2004 Initially named 3GIO (Third Generation Input/Output) high speed connection Used on Pentium 4 motherboards Uses a packetised protocol (8bit/10bit encoding) Starting freqency 2.5GHZ, go up to 10 GHZ Hot plug and hot swappable capability Power management capabilities

PCI 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, x16 x1 bus throughput is 250MB/s * 2 = 500MB/s x4 bus throughput is 1GB/s * 2 = 2GB/s x8 bus throughput is 2GB/s * 2 = 4GB/s x16 bus throughput is 4GB/s * 2 = 8GB/s

PCI Express 2.0 Released 15 January 2007
Doubles the bus standard bandwidth of previous version i.e. x16 bus throughput at 8GB/s * 2 = 16GB/s is backwards compatible Features improvements to the point-to-point data transfer protocol and its software architecture Intel is expected to release its first chipsets supporting PCIe 2.0 in the second quarter of 2007 with its ‘Bearlake’ family AMD starts supporting PCIe 2.0 from its RD700 chipset series NVIDIA has revealed that the MCP72 will be their first PCIe 2.0 equipped chipset

PCI

Bus timeline

Different Input / Output / Storage ports

Serial 1 copper wire slower 1 bit at a time Serial protocol
faster, fewer electrical connections and inherently has no timing skew or crosstalk

Parallel 8 copper wires faster 8 bits at a time
Slower in comparison to Serial packetized protocol

USB Universal Serial Bus
127 devices, daisy chained bus designed to eliminate cable clutter hub 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 commands PnP and hot swappable internal and external In 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 = 480Mbps USB 1.0 is backwards compatible with USB 2.0

Hot 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.[1] 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.

FireWire i.Link or IEEE 1394 different versions of FireWire (FireWire 400, FireWire 800) up to 800Mbps 4.5m cable length 16 cables can be daisy chained up to 72 meters long serial 63 devices hot plug internal and external 4-pin (digital camera) and 6-pin FireWire (PC) power provided

IDE Intelligent / Integrated Device Electronics
Parallel ATA (Advanced Technology Attachment) cheap devices and controllers maximum of 2 drives only supports hard drives maximum of 528MB capacity easy to install and setup slow internal drives only no power provided

EIDE Enhanced IDE Parallel ATA used on Pentiums
cheap drives and controllers maximum of 2 drives for each of the 2 controllers (4 drives) 300GB storage capacities HDD, CD, DVD, Zip drives easy to install and setup 40 cable pins ( wires) internal drives only Ultra/ATA 133 (133MB/s) cable 40cm long bulky, inflexible, fragile and too short not hot swappable 4 pin power connector no power provided

EIDE drives Configure jumpers on EIDE devices (1 hard disk drive and 1 CD-ROM drive)

SATA Serial ATA (internal) up to 1 meter cable length
eSATA (external) up to 2 meter cable length 7 cable pins (4-7 wires) one serial drive per port point-to-point connection connectors are 8mm wide cable thinner and more flexible, provides better airflow connectors are more compact hot-plug capability 1.5Gbps (150MB/s *8 = 1200 = 1.2Gbps + overheads = 1.5Gbps), 3Gbps (300MB/s), 6Gbps (600MB/s) 15-pin power connector supports 8B/10B encoding no power provided

SATA- IDE

SCSI Small Computer Systems Interface use on servers and non-Intel PC
expensive drives and controllers supports 7-15 devices all types of drives (i.e. hard disks, scanners) hard to install and setup fast for servers external drives up to 12 meter cable length (Ultra-320 SCSI = 320MB/s) must use terminator no power provided

SCSI

A SCSI Chain The advantage of SCSI is that several peripherals can be daisy chained to one host adapter, using only one slot in the bus.

RAID Redundant Array of Independent / Inexpensive Disks
Multiple disks accessed in parallel will give greater throughput than a single disk Redundant data on multiple disks provides fault tolerance used in servers or main frames (although can be commonly setup on desktop PCs) provides higher reliability and/or faster access/performance depending on RAID type drives in a RAID system are hot swappable for servers and mainframes RAID appears to the OS as one single logical hard disk 6 standards (RAID 0 to RAID 5) (RAID 1 = mirroring) although can get different combinations of RAID (RAID 10, RAID 53)

RAID

Interrupt / Plug’n’Play

Interrupt 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

Interrupt characteristics
Interrupts can come from a variety of sources The PC supports 256 (0-255) types of interrupts: 15 are hardware interrupts and 241 are software interrupts

5 Interrupt classifications
Highest to lowest Reset button / power button Internal CPU error (overflow) NMI (Non-Maskable Interrupt) - parity error or power fail detect Software INT instruction - interrupt signals initiated by programs External hardware interrupts - IRQ, alt-ctrl-del, keystroke, printer call

Plug and Play A plug and play system is one that can automatically find and configure all of the hardware devices (also called components) in a system.

Before Plug and Play Before 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.

With Plug and Play A 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 process Your 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.

Plug and Play PnP automatic selection of IRQs (and other system resources) previously IRQs were manually selected by jumpers on expansion cards the user had to select an unused IRQ to prevent interrupt conflict to use PnP: require a PnP expansion card, PnP BIOS, PnP OS and PnP motherboard support