From: bgrubb@dante.nmsu.edu (GRUBB)
Subject: Re: IDE vs SCSI
Organization: New Mexico State University, Las Cruces, NM
Lines: 44
Distribution: world
NNTP-Posting-Host: dante.nmsu.edu

wlsmith@valve.heart.rri.uwo.ca (Wayne Smith) writes:
>What does a 200-400 meg 5 megs/sec SCSI drive cost?
Since the Quadra is the only Mac able to deal with 5MB/s and Hard drives START
at 160MB I have NO idea.
For the Mac I have the following {These are ALL external}
 20MB $299 {$15/MB}
 52MB $379 {$7.3/MB}
 80MB $449 {$5.63/MB}
120MB $569-$639 {$4.75-$5.33/MB
210MB $979-$1029{$4.67-$4.90/MB}
320MB $1499-$1549 {$4.68-$4.84/MB}
510MB $1999-$2119 ($3.92-$4.31/MB}
etc

So scsi-1/SCSI-2 for the Mac goes down in price/MB as hard drive size goes
up {and I assume the same for the PC world.}

>I won't argue that the SCSI standard makes for a good, well implimented
>data highway, but I still want to know why it intrinsically better
>(than IDE, on an ISA bus) when it comes to multi-tasking OS's when
>managing data from a single SCSI hard drive.
Well SCSI is ALSO a FLOPPY drive interface.  In the Mac {since SCSI is THE
inteface for any non-card, non-modem, not-keyboard device} the id 7 is used
for the floppy drive {called CPU in all identifiers.}  This allows cross
drive interfacing as fast as the OS, program, CPU, SCSI, and drive can handle 
it{this shows up best in the Quatra line}.
In the IBM that uses SCSI for the FLOPPY drive this should happen as well.
Also SCSI is NOT just drives but printers, scanners, expandsion cards 
{this showed up for the Plus as the NuBus 'Cage'}, CD-ROM, etc.
IDE seems to be mainly hard drives.  As for specs nobody has GIVEN me any
and I can't find any.  Besides the advertizments call IDE the AT interface
{Make of that what you will}
SCSI is a jack of all trades and IDE is a master of ONE.
This alone puts SCSI above IDE.  SCSI-2 blows IDE out of the water.
Remember SCSI was used in high priced machines until about 18 months ago
{When the Mac prices came down to Earth} so the Rule of Scale still played
and SCSI remained high cost{cheap seems to mean chezzy in the High end
computer world at times and THIS more than anything else proably kept SCSI
off into the statosphere price wise}
SCSI came FROM the high end computer world with multitasking OS were the
standard for the most part.  Of all the interface NeXT could have used it
choose SCSI.  In 16-bit and 32-bit mode SCSI is a multi-tasking OS desined
interface while IDE and 8-bit SCSI are braindead run one program interfaces
{at least the way mac use 8-bit SCSI.UGH}
