Princeton ELE 475 - 1 ISA issues

Engineering Principle: ABSTRACTION

Abstrcation of real world computers:

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 ↑ Computer Science

-app software

-algorithm

-high-level language

-OS / virtual machine 

-instruction set architecture (ISA)  ------------------------------------ boundry of hardware and software

-micro-architecture

-digital logic design(RTL)  ----------------------------------------------- boundry of "functional" blocks and basic devices

-gates and circuits design 

-transistor tech(i.e. CMOS)

-quantum physics

↓ Electrical Engineering & Physics

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 Too much details(too low-level) blur understanding; too few details(too high-level) limits understanding.

Switch your view of abstraction layers to focus on central problems.  

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• fundamental machine model

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           -stack: 2 implicit operands

           -accumulator: 1implicit & 1 explicit

           -GPR: 2 explicit operands

           -reg-reg model is also known as load/store

           

• classes of instructions

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• addressing modes

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• data types and sizes

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          -integer, floating points

          -8-bit, 16-bit, 32-bit

• ISA encoding (format)

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          -fixed length

          -variable length

          -VLIW(Very Long Instruction Word)

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for purely SEQUENTIAL computers, clock freq↑, it goes faster, but it also produces more heat, so much heat that a expensive cooling system is demanded

power wall = clock frequency wall = processing speed wall

must employ PARALLELISM ! ! !

• instruction level parallelism
• data level parallelism
• thread level parallelism

Michal Flynn [1966] taxonomy [Today's computers are HYBRID]

• SISD: single instrcution stream & single data stream

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          -uniprocessor

          -can exploit ILP such as superscalar and speculation execution 

• SIMD: single ins. stream & multiple data stream

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          -the same instruction executed by multiple processors using different data streams

          -exploit data-level parallelism by applying the same operations to multiple items of data in parallel

          -multiple data memory & single ins. memory and control unit

• MISD: multiple ins. stream & single data stream

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• MIMD: multiple ins. stream & multiple data stream

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other useful resources:

CS-224 from Bilkent University (youtube podcast series)

ELE-475 from Princeton University (coursera)

Computer Organization and Design - The Hardware Software Interface(5th edition)

Computer Architecture - A Quantitative Approach(5th edition)