Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!bpa!cbmvax!daveh
From: daveh@cbmvax.commodore.com (Dave Haynie)
Newsgroups: comp.sys.amiga
Subject: Re: Real System Comparisons
Message-ID: <13696@cbmvax.commodore.com>
Date: 8 Aug 90 04:10:26 GMT
References: <13466@cbmvax.commodore.com> <EACHUS.90Jul30151024@aries.linus.mitre.org> <MWM.90Aug6155608@raven.pa.dec.com> <90219.131732LEEK@QUCDN.BITNET>
Reply-To: daveh@cbmvax (Dave Haynie)
Distribution: usa
Organization: Commodore, West Chester, PA
Lines: 36

In article <90219.131732LEEK@QUCDN.BITNET> LEEK@QUCDN.QueensU.CA writes:
>In article <MWM.90Aug6155608@raven.pa.dec.com>, mwm@raven.pa.dec.com (Mike (Real
>Amigas have keyboard garages) Meyer) says:

>>1) The standard disk interface for high-end IBM PCs is ESDI, not SCSI.

>Please check up on the ISA SCSI adaptor thread  (recent) on comp.pc.hardware
>(something like that.) The availability of some high performance (up to 10M
>bytes/sec with the adaptor as the bus master (like in Amiga)) seems to indicate
>that there is a market for the high end machines using SCSI as a storage device.
>As always,  PC hardware are market driven...

While SCSI-2 is supposed to be able to manage a high-speed 10 MB/s synchronous
mode, ISA maxes out at 4 MB/s (at least the most accepted ISA, which runs at
8MHz).  In any case, the appearance of high speed disk controllers on PCs other
than Amigas is undoubtedly due to the repositioning of those systems.  Both PCs
and Macs (the Mac IIfx comes with a DMA-driven SCSI of some kind, and bus
mastering NuBus SCSI boards are available) are now offering multitasking OSs,
especially the rather largish UNIX OS.  They find, as we knew all along, that
a CPU driven controller wastes great amounts of system bandwidth even when its
transfer speeds approach those of DMA-driven devices.  And with a paging system
like UNIX, heavy swapping starts making your computer's throughput move toware
that of the backing hard disk rather than that of main memory (you never get 
there; you'd probably throw the thing through a window long before then, but you
do notice the disk overhard much more than in small, vanilla, single-tasking
systems like MS-DOS).

>>        <mike

>K. C. Lee      (Just the facts.  No disclaimers required.)


-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
      Get that coffee outta my face, put a Margarita in its place!