10142

神经网络昆斯林的新闻组分类2006

Newsgroups: comp.os.ms-windows.misc
Path: cantaloupe.srv.cs.cmu.edu!das-news.harvard.edu!noc.near.net!howland.reston.ans.net!usc!cs.utexas.edu!csc.ti.com!tilde.csc.ti.com!mksol!mccall
From: [e-mail] (fred j mccall 575-3539)
Subject: Re: Question on EISA video board performance
Message-ID: <[e-mail]>
Organization: Texas Instruments Inc
References: <[e-mail]> <[e-mail]>
Date: Fri, 30 Apr 1993 21:57:40 GMT
Lines: 42

In <[e-mail]> [e-mail] (charles allen) writes:

>From article <[e-mail]>, by [e-mail] (Christopher F Wroten):
>> I have an EISA machine and I just do not understand why most
>> EISA video cards only match the performance of their ISA
>> counterparts. For instance, the EISA Orchid Pro Designer IIs-E is
>> only about as "fast" as the ISA Diamond SpeedStar Plus, which isn't
>> what I would call "fast."
>> 
>> I don't understand why EISA video cards aren't, as a group, on the
>> same level of performance as Local Bus cards, given that EISA video
>> cards have a 32 bit bus to move data around, instead of ISA's 8 bits.
>> 
>Good question.
>Answer: The EISA bus does move 32 bits rather than ISA's 8/(16?)
>        But it still moves it at about the speed as the ISA bus.
>        I think that's either 8 or 10 mhz.
>        The local bus designs also move 32 bits like the EISA, but
>        they move the data at the cpu speed, up to 40 mhz.
>        So, on a 33mhz cpu, the local bus is moving 32bit data at
>        33 mhz, and the EISA is moving 32bit data at 8 or 10 mhz.
>        So the local bus should be 3 to 4 times faster than EISA on
>        a 33 mhz cpu.  EISA should be about two (maybe 3) times as
>        fast as ISA.

I would expect the EISA board to be more than twice as fast as the ISA
board.  Not only are you moving data on a path twice as wide (at
least), but there is a difference in the number of clocks required for
bus transactions between the two busses.  Most ISA boards require
multiple clocks per bus transaction -- typically this is around 3-4.
EISA boards are suppose to be able to 'burst' at a 1:1 rate, so I
would expect performance to be 6x-8x that of an ISA card.  

So I guess, for me, the question is unanswered still.  I would expect
him to be able to see a 6x speed difference, and he apparently does
not.  

-- 
"Insisting on perfect safety is for people who don't have the balls to live
 in the real world."   -- Mary Shafer, NASA Ames Dryden
------------------------------------------------------------------------------
[e-mail] - I don't speak for others and they don't speak for me.