Interconnection Structures
Interconnection Structures
A computer consists of a set A computer consists of a set of componentsof components
(CPU,memory
(CPU,memory,I/O) that ,I/O) that communicate withcommunicate with each other.
each other.
The collection of paths connecting the The collection of paths connecting the
various modules is call the
various modules is call the interconnectioninterconnection
structure
structure..
The design of this structure will depend on The design of this structure will depend on
the exchange that must be made between the exchange that must be made between modules
Input/Output for each module
Input/Output for each module
Memory Memory N Word N Word 0 0 .. .. .. N-1 N-1 Read Read Write Write Address Address Data Data Data Data CPU CPU Interrupt Signal Interrupt Signal Data Data Data Data Instructions Instructions Control Control Signal Signal I/O Module I/O Module M Ports M Ports Read Read Write Write Address Address Internal Internal Data Data External External Data Data Internal Internal Data Data External External Data Data Interrupt Interrupt Signal Signal
Type of transfers
Type of transfers
Memory to CPU
Memory to CPU
CPU to Memory
CPU to Memory
I/O to CPU
I/O to CPU
CPU to I/O
CPU to I/O
Bus Interconnection
Bus Interconnection
A bus is a communication pathwayA bus is a communication pathway
connecting two or more device. connecting two or more device.
A key characteristic of a bus is that A key characteristic of a bus is that it is ait is a
shared transmission medium. shared transmission medium.
A bus consists of multiple pathways or lines.A bus consists of multiple pathways or lines.
Each line is capable of transmitting signalEach line is capable of transmitting signal
representing binary digit (1 or 0) representing binary digit (1 or 0)
Bus Interconnection
Bus Interconnection
A sequence of bits can be transmit across aA sequence of bits can be transmit across a
single line. single line.
Several lines can be used to transmit bitsSeveral lines can be used to transmit bits
simultaneously (in parallel). simultaneously (in parallel).
A bus that connects major componentsA bus that connects major components
(CPU,Memory,I/O) is called
(CPU,Memory,I/O) is called System BusSystem Bus..
The most common computer interconnection The most common computer interconnection
structures are based on the use
structures are based on the use of one orof one or more system buses.
Bus Structure
Bus Structure
A system bus consists of 50-100 lines.A system bus consists of 50-100 lines.
Each line is assigned a Each line is assigned a particular meaning or function.particular meaning or function.
On any bus the lines can be classified into 3 groupsOn any bus the lines can be classified into 3 groups
Data linesData lines
Address linesAddress lines
Data Lines
Data Lines
Provide a path for moving data between systemProvide a path for moving data between system
modules. modules.
These lines, collectively, are called the These lines, collectively, are called the data busdata bus
The data bus typically consists of 8,16 or 32 The data bus typically consists of 8,16 or 32
separate lines, the numbers of lines being separate lines, the numbers of lines being transferred to as the
transferred to as the widthwidth of the data bus.of the data bus.
Each line carry only 1 bit at a time, the number of Each line carry only 1 bit at a time, the number of
lines determines how many bits can transferred at lines determines how many bits can transferred at a time - overall system performance.
The Address Lines
The Address Lines
Used to designate the source orUsed to designate the source or
destination of the data on the data bus destination of the data on the data bus
The width of the address bus The width of the address bus
determines the maximum possible determines the maximum possible memory capacity of the system.
The Control Lines
The Control Lines
Used to control the access to and the useUsed to control the access to and the use
of the data and address lines. of the data and address lines.
Typical control lines include Typical control lines include
Memory writeMemory write
Memory readMemory read
I/O writeI/O write
I/O readI/O read
ClockClock
ResetReset
Bus requestBus request
Bus grantBus grant
Interrupt requestInterrupt request
Interrupt ACK Interrupt ACK
The operation of the bus
The operation of the bus
If one module wishes to send data If one module wishes to send data
obtain the use of the busobtain the use of the bus
transfer data via the bustransfer data via the bus
If one module wishes to request data If one module wishes to request data
obtain the use of the busobtain the use of the bus
transfer request to the other module over thetransfer request to the other module over the
control and address lines, then wait for
control and address lines, then wait for thatthat second module to send the data.
Physical Bus Architecture
Physical Bus Architecture
System bus is a number of System bus is a number of
parallel electrical conductors. parallel electrical conductors.
The conductors are metal The conductors are metal
lines etched in a card or lines etched in a card or printed circuit board.
printed circuit board.
The bus extends across all of The bus extends across all of
the components tat taps into the components tat taps into the bus lines.
Multiple-Bus Hierarchies
Multiple-Bus Hierarchies
More devices attached to bus, More devices attached to bus, propagationpropagation
delays affect performance delays affect performance
How to arbitration arbitration?How to arbitration arbitration?
Bottleneck as the aggregate dataBottleneck as the aggregate data
transfer demand approaches capacity of transfer demand approaches capacity of
bus. bus. (e.g
(e.g graphics graphics & & video video controller)controller)
Traditional Bus Architecture
Traditional Bus Architecture
Local bus
Local bus
CPU - CacheCPU - Cache
System bus
System bus
Main memory - CacheMain memory - Cache
Expansion bus
Expansion bus
High-Performance Architecture
High-Performance Architecture
Local bus
Local bus
CPU - Cache/bridgeCPU - Cache/bridge
System bus
System bus
Cache/bridge - memoryCache/bridge - memory
High-speed bus
High-speed bus
High-speed I/O module - Cache/bridgeHigh-speed I/O module - Cache/bridge
Expansion bus
Expansion bus
Bus Design
Bus Design
Type
Type
DedicatedDedicated MultiplexedMultiplexed
Bus Width
Bus Width
AddressAddress DataData
Timing
Timing
SynchronousSynchronous AsynchronousAsynchronous
Method of Arbitration
Method of Arbitration
CentralizedCentralized
DistributedDistributed
Data Transfer Type
Data Transfer Type
ReadRead WriteWrite Read-modify-writeRead-modify-write Read-after-writeRead-after-write BlockBlock
Type
Type
Dedicated
Dedicated
permanent assigned bus either
permanent assigned bus either
to one function or to a physical
to one function or to a physical
subset of computer components
subset of computer components
Multiplexed
Multiplexed
use
use
in
in
the
the
same
same
bus
bus
for
for
multiple purpose
Bus Width
Bus Width
Address
Address
the
the
wider
wider
of
of
address
address
bus
bus
has an impact on range of
has an impact on range of
locations that can be referenced
locations that can be referenced
Data
Data
the wider of data bus
the wider of data bus
has an impact on the number
has an impact on the number
of bits transferred at one time
of bits transferred at one time
Timing
Timing
SynchronousSynchronous occurrence occurrence ofof events events on on the the busbus
is determined by a
is determined by a
clock (
clock (Clock Cycle orClock Cycle or
Bus Cycle
Bus Cycle) which) which
includes line upon
includes line upon
AsynchronousAsynchronous occurrence occurrence of one event of one event follows and follows and depends on the depends on the previous event. previous event.
Method of Arbitration
Method of Arbitration
CentralizedCentralized bus controller bus controller ((ArbiterArbiter), hardware), hardware
device,is responsible
device,is responsible
for allocating time
for allocating time
on the bus (daisy
on the bus (daisy
chain) chain) DistributedDistributed access control access control
logic in each module
logic in each module
act together to share
act together to share
bus
Data Transfer Type
Data Transfer Type
Read
Read
Multiplexed
Multiplexed
bus is used to
bus is used to
specifying address and then for
specifying address and then for
transferri
transferri
ng
ng
data
data
after
after
a
a
wait
wait
while
while
data is being fetched
data is being fetched
Read
Read
Dedicated
Dedicated
address is put
address is put
on
on
bus
bus
and
and
remain
remain
there
there
while
while
data
data
are put on the data bus
Data Transfer Type
Data Transfer Type
WriteWrite MultiplexedMultiplexed
bus is used to
bus is used to specifying addressspecifying address
and
and then then transferring transferring data data ((same assame as
read operation
read operation))
WriteWrite DedicatedDedicated
data put on data bus as soon
data put on data bus as soon
as the address has stabilized
Read-modify-writeRead-modify-write
address is broadcast once at beginning a
address is broadcast once at beginning a
simply read is followed immediately by a
simply read is followed immediately by a write towrite to
the same address
the same address
Read-after-writeRead-after-write
a write followed immediately by a read
a write followed immediately by a read
from the same address,performed for checking
from the same address,performed for checking
purposes
purposes
Data Transfer Type
Data Transfer Type
Data Transfer Type
Data Transfer Type
Block
Block
one address cycle is
one address cycle is
followed by
followed by
n
n
data cycles.
data cycles.
The first data item is transferred to
The first data item is transferred to
or from the specified address;
or from the specified address;
remainder
remainder
data
data
items
items
are
are
transferred
transferred
to
to
or
or
from
from
subsequent
subsequent
addresses
Data Transfer Type
Data Transfer Type
no
no
Samples of Bus
Samples of Bus
ISA (Industry Standard Architecture)ISA (Industry Standard Architecture)
MCA (Micro Channel Architecture)MCA (Micro Channel Architecture)
EISA (Extended ISA)EISA (Extended ISA)
VL Bus (VESA Local Bus)VL Bus (VESA Local Bus)
PCI Bus (Peripheral ConnectionPCI Bus (Peripheral Connection
Interface) Interface)
Industry Standard Architecture
Industry Standard Architecture
ISA is a standard busISA is a standard bus (computer(computer interconnection)
interconnection) architecture that isarchitecture that is
associated with the IBM AT motherboard. associated with the IBM AT motherboard.
It allows 16 bits at a tiIt allows 16 bits at a time to flowme to flow
between the motherboard circuitry and between the motherboard circuitry and an expansion slot card and its associated an expansion slot card and its associated device(s).
device(s).
no
no
Industry Standard Architecture
A
A
"local bus"
"local bus"
is a physical
is a physical
path on which data flows at
path on which data flows at
almost the speed of the
almost the speed of the
microprocessor, increasing
microprocessor, increasing
total system performance.
Micro Channel Architecture
Micro Channel Architecture
Developed by IBM for its line of PS/2 desktopDeveloped by IBM for its line of PS/2 desktop
computers, MCA is an interface between a computers, MCA is an interface between a computer (or multiple computers) and its computer (or multiple computers) and its
expansion cards and their associated devices. expansion cards and their associated devices.
MCA was a distinct break from previous busMCA was a distinct break from previous bus
architectures such as ISA. architectures such as ISA.
The pin connections in MCA are smaller than other The pin connections in MCA are smaller than other
bus interfaces. For this and other reasons, MCA bus interfaces. For this and other reasons, MCA does not support other bus architectures.
does not support other bus architectures.
no
no
Micro Channel Architecture
Micro Channel Architecture
(cont.)
(cont.)
Although MCA offers a number of Although MCA offers a number of
improvements over other bus improvements over other bus architectures, its proprietary, architectures, its proprietary,
nonstandard aspects did not encourage nonstandard aspects did not encourage other manufacturers to adopt it.
other manufacturers to adopt it.
It has influenced other bus designs andIt has influenced other bus designs and
it is still in use in PS/2s and in some it is still in use in PS/2s and in some minicomputer systems.
minicomputer systems.
no
no
Extended Industry Standard
Extended Industry Standard
Architecture
Architecture
EISA is a standard bus EISA is a standard bus architecture thatarchitecture that
extends the ISA standard to a
extends the ISA standard to a 32-bit32-bit interface. It was developed in part as
interface. It was developed in part as anan open alternative to the proprietary
open alternative to the proprietary
Micro Channel Architecture (MCA) that Micro Channel Architecture (MCA) that IBM introduced in its PS/2 computers. IBM introduced in its PS/2 computers.
EISA data transfer can reach a peak of EISA data transfer can reach a peak of
33 megabytes per second 33 megabytes per second
no
no
VESA Local Bus
VESA Local Bus
VESA VL bus is a standard interfaceVESA VL bus is a standard interface
between your computer and its e
between your computer and its expansionxpansion slot that provides faster data
slot that provides faster data flow betweenflow between the devices controlled by the expansion
the devices controlled by the expansion
cards and your computer's microprocessor. cards and your computer's microprocessor.
AA "local bus""local bus" is a physical path on whichis a physical path on which
data flows at almost the speed of the data flows at almost the speed of the
microprocessor, increasing total system microprocessor, increasing total system performance.
performance.
no
no
VESA Local Bus (cont.)
VESA Local Bus (cont.)
VESA Local Bus is VESA Local Bus is particularly effective inparticularly effective in
systems with advanced video cards and systems with advanced video cards and supports 32-bit data flow at 50 MHz
supports 32-bit data flow at 50 MHz
A VESA Local Bus is implemented by addingA VESA Local Bus is implemented by adding
a supplemental slot and card that aligns a supplemental slot and card that aligns with and augments an ISA expansion card. with and augments an ISA expansion card. (ISA is the most common expansion slot in (ISA is the most common expansion slot in today's computers.)
today's computers.)
no
no
Peripheral Component
Peripheral Component
Interconnect
Interconnect
PCI is an interconnection systemPCI is an interconnection system
between a microprocessor and attached between a microprocessor and attached devices in which expansion slot are
devices in which expansion slot are
spaced closely for high speed operation. spaced closely for high speed operation.
Using PCI, a computer can support bothUsing PCI, a computer can support both
new PCI cards while continuing to new PCI cards while continuing to
support ISA expansion cards, currently support ISA expansion cards, currently the most common kind of expansion the most common kind of expansion card.
Peripheral Component Interconnect
Peripheral Component Interconnect
(cont.)
(cont.)
Designed by Intel, the original PCI was similar to theDesigned by Intel, the original PCI was similar to the
VESA Local Bus. VESA Local Bus.
PCI2.0 is no longer a local bus and is designed to bePCI2.0 is no longer a local bus and is designed to be
independent of microprocessor design. independent of microprocessor design.
PCI is designed to be synchronized with the clockPCI is designed to be synchronized with the clock
speed of the microprocessor, in the range of 33 to speed of the microprocessor, in the range of 33 to 66 MHz.
66 MHz.
Standard : Up to 64 data-lines at 66 MHz. RawStandard : Up to 64 data-lines at 66 MHz. Raw
transfer
Peripheral Component Interconnect
Peripheral Component Interconnect
(cont.)
(cont.)
PCI is now installed on most newPCI is now installed on most new
desktop computers, not only those desktop computers, not only those
based on Intel's Pentium processor but based on Intel's Pentium processor but also those based on the PowerPC.
also those based on the PowerPC.
PCI transmits 32 bits at a time in PCI transmits 32 bits at a time in a 124-a
124-pin connection (the extra 124-pins are for pin connection (the extra pins are for power supply and grounding) and 64 power supply and grounding) and 64 bits in a 188-pin connection in an
bits in a 188-pin connection in an expanded implementation.
Peripheral Component Interconnect
Peripheral Component Interconnect
(cont.)
(cont.)
PCI uses all active paths to transmitPCI uses all active paths to transmit
both address and data signals, sending both address and data signals, sending the address on one clock cycle and data the address on one clock cycle and data on the next.
on the next.
PCI deliver better system performancePCI deliver better system performance
for high-speed I/O subsystems for high-speed I/O subsystems e.g.
e.g. graphic display adaptersgraphic display adapters,, networknetwork
interface controllers
PCI
PCI
Single-processo
Single-processor r SystemSystem
A Multiprocessor System A Multiprocessor System
Interface
Interface
Port Port SerialSerial ParallelParallel PS/2PS/2 PCMCIAPCMCIA USBUSB (Universal Serial (Universal Serial Bus) Bus) No port No port InfraredInfrared BluetoothBluetoothUniversal Serial Bus
Universal Serial Bus
Standard bus which is invented by a group of companies :Standard bus which is invented by a group of companies :
Compaq, DEC, IBM, Intel, Microsoft, NEC, Northern Compaq, DEC, IBM, Intel, Microsoft, NEC, Northern Telecom, etc.
Telecom, etc.
Not change switch, jumper on board or other devicesNot change switch, jumper on board or other devices
Can use the same cableCan use the same cable
Device that use USB can use power supply from PC.Device that use USB can use power supply from PC.
Up to 127 devices connected off single portUp to 127 devices connected off single port
Support real-time systemSupport real-time system
Hot Plug-inHot Plug-in
Low costLow cost
no
no
Multi-System Buses
Accelerated Graphics Port
Accelerated Graphics Port
AGP is an interface specification that enables 3-DAGP is an interface specification that enables 3-D
graphics to display quickly on ordinary PC. graphics to display quickly on ordinary PC.
AGP is an interface designed to convey 3-D imagesAGP is an interface designed to convey 3-D images
(ex:-from Web sites or CD-ROMs) much more quickly (ex:-from Web sites or CD-ROMs) much more quickly and smoothly than is possible today on any computer and smoothly than is possible today on any computer other than an expensive graphics workstation.
other than an expensive graphics workstation.
The interface uses your computer's main storage The interface uses your computer's main storage
(RAM) for refreshing the monitor image and to support (RAM) for refreshing the monitor image and to support the
the texture mappingtexture mapping,, z-buffering z-buffering,, andand alpha blendingalpha blending required for 3-D image display.
required for 3-D image display.
no
no
Accelerated Graphics Port (cont.)
Accelerated Graphics Port (cont.)
The AGP main memory use is dynamic, meaning that when not The AGP main memory use is dynamic, meaning that when not being used for accelerated graphics, main
being used for accelerated graphics, main memory is restoredmemory is restored for use by the operating system or other applications.
for use by the operating system or other applications.
Intel, which has taken the lead in developing its specifications,Intel, which has taken the lead in developing its specifications, introduced AGP into a chipset for its Pentium microprocessor. introduced AGP into a chipset for its Pentium microprocessor.
The newer, faster microchips in The newer, faster microchips in Pentium line are designed toPentium line are designed to work with the AGP chipset. Intel says the advanced floating work with the AGP chipset. Intel says the advanced floating point unit and faster cache algorithm of the more advanced point unit and faster cache algorithm of the more advanced Pentiums are better adapted for 3-dimensional applications. Pentiums are better adapted for 3-dimensional applications.
