Clockless Computing

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Clockless Computing

• Montek Singh
• Thu, Sep 20, 2007

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More on Asynchronous Pipelines(one classic and
two latest approaches)

• Sutherlands micropipelines
• 1989 Turing Award lecture
• Sutherland et al.s GasP pipelines
• 2001 ASYNC Best Paper Award
• IBMs IPCMOS pipelines
• 2000 very highly publicized holds current
  record for speed

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Sutherlands Micropipelines (1989)

• Basic FIFO (no logic)

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Sutherlands Micropipelines (1989)

• Pipeline with logic
• Also more robust construction

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Sutherlands Micropipelines (1989)

• Details of the storage elements
• capture-pass latches

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GasP PipelinesSutherland Fairbanks 2001

• A minimal control circuit for pipelines
• Very highly regarded cool
• But fairly low-level design
• Transistor level
• Stringent (2-sided) timing requirements

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GasP A Pipeline Stage
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GasP Controller Details
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IPCMOS (IBM 2000)

• Interlocked Pipelined CMOS
• Really fast 3.3GHz in 0.18?
• Even faster (4.5GHz) for extreme corner cases
• Bragging rights!
• But very low-level design
• Transistor-level design
• Stringent (2-sided) timing constraints
• Not clear if it really should be that fast!
• Technology-independent comparison unsure if
  faster than GasP

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IPCMOS A Pipeline Stage
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IPCMOS Controller Details
ackin
reqout
X
En
(latchenable)
R1
Rn
A
switch
switch
ackout
reqinn
reqin1
pulse catcher
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IPCMOS Pulse Catcher