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 transistor technology 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 Computer High Level Language Program Assembly Language Program Machine Language Program Hardware Compiler Assembler Machine Interpretation lw$15,0($2) lw$16,4($2) sw$16,0($2) sw$15,4($2) temp = v[k]; v[k] = v[k+1]; v[k+1] = temp; ALUOP[0:3] <= InstReg[9:11] & MASK ISA

Java High Level Language Program Assembly Language Program Java Byte Code Hardware Compiler Assembler Virtual Machine Interpretation lw$15,0($2) lw$16,4($2) sw$16,0($2) sw$15,4($2) temp = v[k]; v[k] = v[k+1]; v[k+1] = temp; 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 217mm 2 in 0.18-micron technology. A new 0.13-micron fab process should cut the die area in half. If defects occur 1 per cm 2, 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 -> > > 0010 Flip all the bits, add one. It works both directions 5 -> -5 -> 5 ____ ____ _____