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

Width number of data bits that can be sent along

the bus at once (i.e. 8, 16, 32, 64bits)

Bus performanceBus throughput

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

Control signalswhich component the data is forwhere blocks of data start and endany other information related to the data

being transferred

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 parallelSerial buses

carry data in bit-serial formParallel buses

carry data words striped across multiple wires

problem: crosstalk across multiple wires

BSB and FSB

BSBBack Side BusThe bus that connects the processor to

the different levels of cacheFound on the processor chip

FSBFront Side BusThe bus that connects the processor to

the different hardware components found on the motherboard

Expansion bus

Expansion busA collection of wires and protocols that

allows the expansion of a computer by inserting printed circuit boards (expansion boards)

http://www.webopedia.com/TERM/Eexpansion_bus.html

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

VESA PCI

Maximum of 3 slots Maximum of 8 to 10 slots

Long, ISA and PC busbackwards compatible

Shorter, more compactconnector

Developed before PnP Supports PnP

Used only on 486processors

Used on Pentium classprocessors

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 AGPPCI AGP

Non-pipelined requests 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

http://en.wikipedia.org/wiki/PCI_Express

PCI

Bus timeline

Different Input / Output / Storage ports

Serial1 copper wireslower1 bit at a time

Serial protocol faster, fewer electrical connections and

inherently has no timing skew or crosstalk

Parallel8 copper wires faster8 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 (40- 80 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 drivesConfigure 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 ChainThe 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 PlayA 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