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  1. I/O Overview

The computer system’s I/O architecture is its interface to the outside world. The I/O components consist the buses, the keybroads, CRT Minitor, Flat panel display, scanner, modem …The I/O architecture consiste the buses and a set of I/O modules, each module interfaces to the bus system or to the outside world.

  • There are 3 principal I/O techniques:

- Programmed I/O

- Interrupt-dreiven I/O

- Direct Memory Access (DMA)

  • There are two I/O techniques.

I/O parallel

I/O serial

  1. Buses

The collection of paths that connect the system modules together form the interconnection structure.

  • Bus Interconnection

Computer systems contain a number of buses that provide pathways between


– Shared transmission media connecting 2 or more devices together

– Broadcast, 1-to-all operation

– Must insure only 1 device places information onto a bus at any given time

  • Typical buses consist of 50-100 lines

- Address information (address bus)

Specifies source/destination of data transfer

Width determines the capacity of the system

– Data information (data bus)

Width is key in determining overall performance

– Control information: Controls access to and use of the address and data bus

– Miscellaneous: power, ground, clock

  • Bus performance and limitations

The performance is limited by:

+ Data propagation delay through the bus longer buses (to support more devices) require longer delays

+ Aggregate demand for access to the bus from all devices connected to the bus

multiple buses To avoid bottlenecks,

  • Multiple Buses:

– Hierarchical

– High-speed limited access buses close to the processor

– Slower-speed general access buses farther away from the processor.

  • External Bus - PC bus

ISA (Industrial Standard Architecture)

– First open system bus architecture for PCs (meaning IBM-type machines)

– 8-bit and 16-bit ISA buses

Figure 13.2 ISA Bus

- Micro Channel Architecture


  • VESA Video Local Bus
  • Bus architecture and organization

Figure 13.1 Hierarchical bus configurations

Questions & Answers

Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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Source:  OpenStax, Computer architecture. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10761/1.1
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