Re: Cells compared to Flow-Based Programming

On Thu, 29 May 2008 11:26:53 -0400, Paul Tarvydas
<tarvydas@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

Do you happen to know anything about hardware design? TTL, say. On a
circuit board populated with TTL chips, are the chips all synchronized or
are they asynchronous?

TTL is not asynchronous in the manner that software people generally
use the term.

In an unclocked design each part is slaved to the part(s) that provide
input to it. Any directed web of TTL logic is synchronous relative to
stability of its input - the propagation time to produce a result once
input stabilizes is predictable. The only really independent circuits
are loops with no external inputs - such as fixed frequency
oscillators - and even then the individual TTL components of the macro
loop circuit are themselves synchronous relative to one another.

A hardware analogy more in keeping with a software discussion would be
two incompatibly clocked macro parts with handshaking data transfer
between them.


Do hardware people achieve better success rates in
their designs than software people do in their designs?

Yes. But the reason is because they don't invent new logic but simply
reuse standardized components having known behaviors. Even when the
components are interconnected in novel ways, the behavior of the
result is predictable.


Do chip designers offer some kind of guarantee that their chips will work as
specified in the data sheets?

No. They offer "warranty" ... which is a very different concept from
"guarantee".


Do software designers offer equivalent guarantees?

No. But some select few do offer warranty.

George
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