Last Lecture COMP375 Computer Architecture

and Organization

“I can remember the exact instant

when I realized that a large part of

my life from then on was going to

be spent in finding mistakes in my

own programs.”

Maurice Wilkes inventor of microcode

Final Exam

The final exam is from 10:30am to 12:30pm on Tuesday, May 10, 2012

You are allowed one 8½ by 11 inch page of notes.

Teaching Evaluation

Be sure to complete the official University teaching evaluation for all of your classes.

The survey is scheduled to end on May 7, 2012, at 8:00am

See your A&T email for details

gestalt

(gesh-TALT) noun

Shape or pattern; most often used in

psychology to describe a theory or

approach which aims to see something as

a whole rather than breaking it into

separate parts

wordsmith.org

The Computer is Not a Black Box

Clock and Architecture

Contributions to Performance

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1987 1989 1991 1993 1995 1997 1999 2001 2002 2003

Clock

Architecture

Machine Language is Executed

• It doesn’t really matter what high level

language you use, it is machine language

that the computer executes.

• Optimization is important. A good compiler

can convert your high level language into

efficient machine language.

Simple CPU

CPU with Cache

CPU with Virtual Memory

Detail of Microcode Store

Microcode Control

Multiple Registers

Interrupts

Memory Hierarchy

Cache & Virtual Memory

• The more cache and memory the better.

• Consider locality of reference

Pipelining and Multiprocessors

• Intel is very interested in Universities

teaching multithread programming to take

advantage of multi-core machines.

• It doesn’t matter how many processors

you have if you are only executing one

thread.

• For high performance applications, there

are techniques for improving pipelining.

Disk Performance

• Seek time is the largest component of

reading a disk, followed by rotational delay

• CDs have long seek times. When reading

short files, the times dependent on the spin

speed don’t matter.

• Read and write large blocks when possible

RAID will Help

• RAID disk systems will help prevent data

loss.

• RAID will not protect you from most data

loss problems, such as data corruption

and user error.

Security

• Security is becoming more and more

important.

• Learn to use the tools available.

No Magic

• The operation of the CPU is just a

sequence of micro-steps.

• RISC processors are becoming more

prevalent.

Layers

• Applications

• Middleware – other CS classes

• High level languages

• Machine Language – COMP375

• Microcode

• Logic circuits

• Gates – COMP370 or ELEN327

• Transistors

• Silicon structures

Incentive for Dual Core • Intel reports that underclocking a single

core by 20 percent saves half the power

while sacrificing just 13 percent of the

performance.

Source: IEEE Spectrum April, 2008

Final Exam

The final exam is from 10:30am to 12:30pm on Tuesday, May 10, 2012

You are allowed one 8½ by 11 inch page of notes.

The exam covers material from the entire semester.

Anything covered in lecture could be on the final exam.

Likely Final Exam Questions

• Write a program in assembler

• How long does it take to read from a disk

• How long does it take to fetch data over

the bus? How fast can the computer run?

• Yet another microcode table

What’s New?

• Engineers are constantly improving the

hardware. Computer Scientist are

constantly improving the software.

22 nm Chips

• Intel has invented a new technology to

create integrated circuits with features that

are 22 nanometers in size.

• A new insulator replaces silicon dioxide

– Insulator is 5 atoms thick

• This also improves power leakage.

Transistor Operation

When positive voltage is applied to the gate,

electrons are attracted to the gate. The

presence of electrons allows current to flow

between the source and drain.

Quantum Physics

Electron Tunneling

• There is a probability that an electron

exists on the other side of a barrier even if

it never crossed the barrier.

Teaching Evaluation

Be sure to complete the official University teaching evaluation for all of your classes.

The survey is scheduled to end on May 7, 2012 at 8:00am

See your A&T email for details

Final Exam

The final exam is from 10:30am to 12:30pm on Tuesday, May 10, 2012

You are allowed one 8½ by 11 inch page of notes.

Words of Wisdom

• Remember those powers of 2

• Back up your data. You’ll be glad you did.

• Good luck on all your finals.