CELL(diagrams from IBM)

Andrew Williams

A.Williams@bolton.ac.uk

CELL partners

Sony, IBM, Toshiba We all know why Sony wants the

CELL– What is IBM’s angle?– What about Toshiba – what do they want

out of the CELL?

CELL chip image

What is this?

PPU

Power Processing Unit– Where might you have expected to find

one of these a couple of years ago?

SPE questions

Each SPE has 128 128-bit registers– What is a register anyway?

• Name an example from an x86 compatible CPU

– How many bytes per register?– 128-bits seems a lot (modern desktop

CPUs have 64-bit registers)• Why does it need 128-bit registers?

This is an SPE: 256K?? What the….?!

Multiplying a matrix by a vertex

void Matrix4f::multiply(const Vector4f vec4f, Vector4f *resultVector) {float *vD = (float *)vec4f.data; // Just for convenience

resultVector->data[0] = data[0]*vD[0] + data[1]*vD[1] + data[2]*vD[2] + data[3]*vD[3];resultVector->data[1] = data[4]*vD[0] + data[5]*vD[1] + data[6]*vD[2] + data[7]*vD[3];resultVector->data[2] = data[8]*vD[0] + data[9]*vD[1] + data[10]*vD[2] + data[11]*vD[3];resultVector->data[3] = data[12]*vD[0] + data[13]*vD[1] + data[14]*vD[2] + data[15]*vD[3];

};

SPE FP performance

A CELL can handle 250GFLOPS as long as you’re happy with SP

Translate that into English– What (according to IBM) is the likely

performance penalty if you really want DP FP?

EIB

EIB questions

What is the clock speed of the PS3 CELL?

What is the clock speed of the EIB? How is the theoretical maximum

bandwidth calculated? How many concentric data pathways

(rings) are there in the EIB? How many data transfers can run

concurrently on each ring?

EIB questions (continued)

Give examples of the sorts of activity that could reduce the bandwidth of the EIB

RSX

What is the RSX? Who developed the RSX? Which consumer PC product is most

like the RSX? What does the design of the RSX say

about the work that the SPEs are likely to be doing?

PS3 and Backwards Compatibility

PS2 is the biggest selling home console

PS2 has the biggest library of games Microsoft’s XBOX XBOX360

compatibility issues

All good reasons why Sony would want to ensure that the PS3 can run PS2 games

PS3 and Backwards Compatibility

American PS3 motherboard includes a chip labelled EE/GS

EE/GS

What does EE/GS mean?

PS3 and Backwards Compatibility

On the European model that chip is absent:

ZOMG!!!

PS3 and the PS2 – What Gives?

If the EE/GS isn’t there, what happens to backwards compatibility in European (and later American) versions?– How is it done?– What are the advantages and

disadvantages?