Computer Architecture II CSC/CPE 315

Where software and hardware finally meet

Prof. Franklin

Chapter 1 – Fabrication

What is Computer Architecture?Program software

Write compilers

Design assembly language

Design processor

Optimize layout, circuits, etc

Design transistortechnology

Architecture

Instruction Set Architecture

• Provides a view of the computer to the compiler/programmer

• Performance– Compiler optimizations– Hardware optimizations

• Price– Implementation difficulty (labor)– Implementation size (manufacturing)

Processor Design

• Where software and hardware meet• Memory system, bus structure, chip

design• High-level ISA implementation (P1 vs P2)• Performance

– Cache size, # of func units, bells & whistles

• Price– Implementation difficulty (labor)– Implementation size (manufacturing)

Hardware Implementation

• Detailed logic design

• Performance– Low-level optimizations

• Price– Packaging technology

CPE 315 Topics

• What do high-level instructions get compiled down to?

• How do you build a basic machine?

• How do architects specialize the hardware to run programs quickly?

• How do programmers optimize programs to run quickly?

How to Speak ComputerHigh Level Language

Program

Assembly Language Program

Machine Language Program

Hardware

Compiler

Assembler

Machine Interpretation

lw $16, 4($2)sw $16, 0($2)sw $15, 4($2)

temp = v[k];v[k] = v[k+1];v[k+1] = temp;

1000110001100010000000000000000100011001111001000000000000010010101100111100100000000000000001010110001100010000000000000100

ALUOP[0:3] <= InstReg[9:11] & MASK

ISA

JavaHigh Level Language

Program

Assembly Language Program

Java Byte Code

Hardware

Compiler

Assembler

Virtual Machine Interpretation

lw $16, 4($2)sw $16, 0($2)sw $15, 4($2)

temp = v[k];v[k] = v[k+1];v[k+1] = temp;

1000110001100010000000000000000100011001111001000000000000010010101100111100100000000000000001010110001100010000000000000100

ALUOP[0:3] <= InstReg[9:11] & MASK

Java ISA

Java Virtual Machine Software translates each instruction

for the current hardware

ISA Machine Interpretation

Architecture

• Where software and hardware meet

• Must understand software– Programs have certain characteristics– Optimize design to take advantage of char.

• Must understand hardware– Hardware design complexity– Ease of programming– Performance– Power

Performance

• Not an absolute• Depends on application characteristics

– Graphics– General-Purpose desktop– Scientific apps– Servers

• Rapidly changing technology– DRAM speed, chip density, etc.

• This is the focus of our class

But I’m CS

• Why do I have to learn about hardware?(I hear you ask)

• Hardware is optimized to take advantage of _________________________

• If your software is different, it can get ___________ performance

• You must _________ general architecture to _________ for it.

• In ideal world, ________ would do this for you.

Which is faster?

R1 = A[5];

B[6] = R1

R3 = R0 + R2

R5 = R4 – R3

R7 = R0 + R6

C[7] = R7

R1 = A[5];

R3 = R0 + R2

R7 = R0 + R6

B[6] = R1

R5 = R4 – R3

C[7] = R7

Which is faster in C/Java?

for(i=0;i<n;i++) for(j=0;j<n;j++) A[j][i] = i*j+7;

for(i=0;i<n;i++) for(j=0;j<n;j++) A[i][j] = i*j+7;

What data structure should I use?

• Array or linked structure?

• Does it change often?

• Does it get searched often?

Growing Silicon

• Silicon is a ______ grown in a vat

• It comes out the shape of a ______

• This is called an ________

Creating Chips

• Sliced into thin discs called ______

• Etch grooves and pour metal, etc

• Cut the wafer into ______ or ______

• A flaw is called a _________

• The percentage of good ones is _______

Price vs Cost

• Price– Selling price– Supply & Demand– Little correlation to fabrication cost

• Cost– Fabrication cost– Design cost

Cost

• Cost per die

• Dies per wafer

• Yield

• Cheapest when Yield and Dies per wafer are (high / low)

Current chip trends

• Shrinking Technology–Reported in ________

–Each generation allows more to fit in same space

–_____________ gradually falls in time with same technology

Current chip trends

• Increasing Area effects:–Yield – (increases / decreases)

chance of a defect on die

–Dies/wafer – (more / fewer) dies, (more / less) wasted space

Example

• Current P4’s are 217mm2 in 0.18-micron technology. A new 0.13-micron fab process should cut the die area in half. If defects occur 1 per cm2, what are the old and new yields?

• Yield = 1 / (1 + (defectrate*area/2)) 2

OldYield:

Technology trends

• Smaller is faster, cheaper– Faster –

– Cheaper –

• Bigger holds more

• Complexity is more accurate, but large & expensive

New Yield:

Review: Two’s complement

• 2 -> -2 -> 2

• 0010 -> 1110 -> 0010

• Flip all the bits, add one. It works both directions

• 5 -> -5 -> 5

• ____ ____ _____