26 Oct
1999
26 Oct
'99
3:55 a.m.
At 10:08 PM 10/25/99 -0700, you wrote:
>>Two 1MHz busses will be faster than a single 2MHz bus if they are being used
>>for different purposes, such as one for I/O and one for memory accesses.
>
>But my point is that one 4 MHz synchronous bus is going to be faster than
>two 1 MHz busses in all cases.
No, no and no.
Yes, yes, and yes.
A dumb 4Mhz burst bus that requires cpu attention to
work
will be many times slower in actual applications than two 1Mhz buses with
distributed arbitration and such smarts. That's all the point of the
discussion. That's why raw numbers tend to be meaningless. That's why
system designers nowadays make decisions based on simulations and not
on raw specs.
Carlos, my man, I find this style of discussion disingenuous. In the absence
of any other data, when somebody says that two 1 MHz busses are better than
one 2 MHz bus, then we must assume that all other conditions are equal.
If, indeed, it's possible to arbitrarily inject post-conditions into our
discussions, then, OF COURSE you can destroy an argument, because you are
making an argument against something that was not supported in the first
place!
Now, I have proven to the satisfaction of everybody that, ASSUMING
synchronous buses that are identical in every way except speed
(one being twice as fast as the two half-speed busses) that in two
real-life situations, one faster bus is BETTER than two separate busses.
-----
I'm waiting for somebody who knows what he/she is talking about on this
issue and provides data, assumptions, references, and, if necessary,
simulation software, etc.
Opinions and vague handwaving won't do for me anymore, sorry.
Carlos.
-Mike "Hard Data, Please!" Cheponis