DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
II YEAR CSE
III SEMESTER
U23CST31-COMPUTER ARCHITECTURE & ORGANIZATION
UNIT I OVERVIEWAND INSTRUCTIONS
EIGHT IDEAS
1. Design for Moore'sLaw
The one constant for computer designers is rapid change, which is driven largely by Moore's Law.
It states that integrated circuit resources double every 18–24months.
Moore's Law resulted from a 1965 prediction of such growth in ICcapacity.
Moore's Law made by Gordon Moore, one of the founders ofIntel.
As computer designs can take years, the resources available per chip can easily double
or quadruple between the start and finish of theproject.
Computer architects must anticipate this rapidchange.
Iconused:"upandtotheright"Moore'sLawgraphrepresentsdesigningforrapidchange.
2. Use Abstraction to SimplifyDesign
,Both computer architects and programmers had to invent techniques to make themselves more
productive.
A major productivity technique for hardware and soft ware is to use abstractions to
represent the design at different levels ofrepresentation;
lower-level details are hidden to offer a simpler model at higherlevels.
Icon used: abstract paintingicon.
3. Make the common casefast
Making the common case fast will tend to enhance performance better than optimizing
the rarecase.
The common case is often simpler than the rare case and it is often easier toenhance
Common case fast is only possible with careful experimentation andmeasurement.
Icon used: sports car ss the icon for making the common case fast(as the most common
trip has one or two passengers, and it's surely easier to make a fast sports car than a fast
minivan.)
4. Performance viaparallelism
,computer architects have offered designs that get more performance by performing operations in
parallel. Icon Used: multiple jet engines of a plane is the icon for parallel performance.
5. Performance viapipelining
Pipelining- Pipelining is an implementation technique in which multiple instructions
are overlapped in execution. Pipelining improves performance by increasing instruction
throughput.
For example, before fire engines, a human chain can carry a water source to fire much
more quickly than individuals with buckets running back andforth.
IconUsed:pipelineiconisused.It isasequenceofpipes,witheachsectionrepresenting one
stage of thepipeline.
6. Performance viaprediction
Followingthesayingthatitcanbebettertoaskforforgivenessthantoaskforpermission, the
next great idea isprediction.
Insomecasesitcanbefasteronaveragetoguessandstartworkingratherthanwaituntil you
know forsure.
This mechanism to recover from a misprediction is not too expensive and theprediction
is relativelyaccurate.
, Icon Used:fortune-teller's crystal ball ,
7. Hierarchy of memories
Programmers want memory to be fast, large, and cheap memory speed often shapes
performance, capacity limits the size of problems that can be solved, the cost of memory
today is often the majority of computercost.
Architects have found that they can address these conflicting demands with a hierarchy
of memories the fastest, smallest, and most expensive memory per bit is at the top of the
hierarchy the slowest, largest, and cheapest per bit is at thebottom.
Caches give the programmer the illusion that main memory is nearly as fast as the top
of the hierarchy and nearly as big and cheap as the bottom of thehierarchy.
Icon Used: a layered triangle icon represents the memoryhierarchy.
The shape indicates speed, cost, and size: the closer to the top, the faster and more
expensive per bit the memory; the wider the base of the layer, the bigger thememory.
8. Dependability viaredundancy
Computers not only need to be fast; they need to be dependable.
Since any physical device can fail, systems can made dependable by including redundant
components.
These components can take over when a failure occurs and to help detectfailures.
II YEAR CSE
III SEMESTER
U23CST31-COMPUTER ARCHITECTURE & ORGANIZATION
UNIT I OVERVIEWAND INSTRUCTIONS
EIGHT IDEAS
1. Design for Moore'sLaw
The one constant for computer designers is rapid change, which is driven largely by Moore's Law.
It states that integrated circuit resources double every 18–24months.
Moore's Law resulted from a 1965 prediction of such growth in ICcapacity.
Moore's Law made by Gordon Moore, one of the founders ofIntel.
As computer designs can take years, the resources available per chip can easily double
or quadruple between the start and finish of theproject.
Computer architects must anticipate this rapidchange.
Iconused:"upandtotheright"Moore'sLawgraphrepresentsdesigningforrapidchange.
2. Use Abstraction to SimplifyDesign
,Both computer architects and programmers had to invent techniques to make themselves more
productive.
A major productivity technique for hardware and soft ware is to use abstractions to
represent the design at different levels ofrepresentation;
lower-level details are hidden to offer a simpler model at higherlevels.
Icon used: abstract paintingicon.
3. Make the common casefast
Making the common case fast will tend to enhance performance better than optimizing
the rarecase.
The common case is often simpler than the rare case and it is often easier toenhance
Common case fast is only possible with careful experimentation andmeasurement.
Icon used: sports car ss the icon for making the common case fast(as the most common
trip has one or two passengers, and it's surely easier to make a fast sports car than a fast
minivan.)
4. Performance viaparallelism
,computer architects have offered designs that get more performance by performing operations in
parallel. Icon Used: multiple jet engines of a plane is the icon for parallel performance.
5. Performance viapipelining
Pipelining- Pipelining is an implementation technique in which multiple instructions
are overlapped in execution. Pipelining improves performance by increasing instruction
throughput.
For example, before fire engines, a human chain can carry a water source to fire much
more quickly than individuals with buckets running back andforth.
IconUsed:pipelineiconisused.It isasequenceofpipes,witheachsectionrepresenting one
stage of thepipeline.
6. Performance viaprediction
Followingthesayingthatitcanbebettertoaskforforgivenessthantoaskforpermission, the
next great idea isprediction.
Insomecasesitcanbefasteronaveragetoguessandstartworkingratherthanwaituntil you
know forsure.
This mechanism to recover from a misprediction is not too expensive and theprediction
is relativelyaccurate.
, Icon Used:fortune-teller's crystal ball ,
7. Hierarchy of memories
Programmers want memory to be fast, large, and cheap memory speed often shapes
performance, capacity limits the size of problems that can be solved, the cost of memory
today is often the majority of computercost.
Architects have found that they can address these conflicting demands with a hierarchy
of memories the fastest, smallest, and most expensive memory per bit is at the top of the
hierarchy the slowest, largest, and cheapest per bit is at thebottom.
Caches give the programmer the illusion that main memory is nearly as fast as the top
of the hierarchy and nearly as big and cheap as the bottom of thehierarchy.
Icon Used: a layered triangle icon represents the memoryhierarchy.
The shape indicates speed, cost, and size: the closer to the top, the faster and more
expensive per bit the memory; the wider the base of the layer, the bigger thememory.
8. Dependability viaredundancy
Computers not only need to be fast; they need to be dependable.
Since any physical device can fail, systems can made dependable by including redundant
components.
These components can take over when a failure occurs and to help detectfailures.
