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From: skraw@thiger.UUCP (Stephan von Krawczynski)
Newsgroups: comp.sys.amiga.hardware
Subject: Re:   GVP Trade-in
Message-ID: <02102.123056@thiger.UUCP>
Date: 20 Aug 90 16:00:56 GMT
References: <1898@lpami.wimsey.bc.ca>
Organization: THIndustries Software Development
Lines: 60

>In article <1898@lpami.wimsey.bc.ca> lphillips@lpami.wimsey.bc.ca (Larry Phillips) writes:
>In <02048.002057@thiger.UUCP>, skraw@thiger.UUCP (Stephan von Krawczynski) writes:
>>2. why is DMA so important for you? it is generally slower than the
>>processor-method (lets call it this way). you win nothing because you
>>have a whole lot of DMA going on already inside the system and processor's
>>running into heavy troubles sometimes, e.g. harddisk-performance is
>>very low while using overscan-graphics (just to mention an example).

this was a typical "late-night"-statement. of course what i wanted to say
was: DMA (other than bitmap) runs into heavy troubles sometimes during
overscan-graphics (e.g.)

>You are completely wrong in this. Not only is DMA faster,[...]

right, but bus-arbitration breaks it completely up.

>Do not confuse one particular implementation of a
>DMA controller, which did have a significant problem under heavy DMA
>conditions, for the entire spectrum of controllers.

i have seen no dma-controller yet, that didn't have problems.

>>well, how about "transfer rates up to 4MB/SEC synchronous" (gvp). in fact
>>i have never understood this one. what do they mean? 4MBytes/sec?
>
>No. they mean 4 MBytes per second, and that is indeed realistic. Of course you
>have to realize that they are not taking about sustained troughput, but about
>the actual data transfer rate as seen on the SCSI bus, from a Controller to
>Host Adapter.

i know this. but tell me: is it really interesting for the customer to hear
somthing about the scsi-bus-transferrate. especially if the controller-to-
amigamem troughput brings the thing down to some 100 kBytes (a typical
bottle-neck). let's talk about the real throughput, not some
part of the story.

>>i have never seen a controller/hd-combination reaching this.
>
>Several do it all the time. Note the difference between SCSI bus transfer rates
>and disk to destination throughput.

i note, but can a (technically uninformed) custumer?

>>4MBits/sec = 512kBytes/sec. seems to be more like the truth, but is an
>>absolutely ridiculous value (ALF3 makes over 200kBytes/sec more in a
>>standard amiga - NO processor-card installed)
>>i think it's a reputable company, what do you think?
>
>Reputable probably. Slow, definitely.
                     
ah, there it is.

>-larry

--
best regards, 
stephan von krawczynski 

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