gauging interest in VAX 6000-530

From: Mike Cheponis <mac_at_Wireless.Com>
Date: Tue Oct 26 10:55:23 1999

>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
Received on Tue Oct 26 1999 - 10:55:23 BST