From: richk@grebyn.com (Richard Krehbiel)
Subject: Re: IDE vs SCSI
In-Reply-To: wlsmith@valve.heart.rri.uwo.ca's message of Thu, 15 Apr 1993 23:55:09 GMT
Lines: 38
Organization: Grebyn Timesharing, Inc.

In article <1993Apr15.235509.29818@julian.uwo.ca> wlsmith@valve.heart.rri.uwo.ca (Wayne Smith) writes:

>   In article <1qk7kvINNndk@dns1.NMSU.Edu> bgrubb@dante.nmsu.edu (GRUBB) writes:
>   >>point of view, why does SCSI have an advantage when it comes to multi-
>   >>tasking?  Data is data, and it could be anywhere on the drive.  Can
>   >>SCSI find it faster?  can it get it off the drive and into the computer
>   >>faster?  Does it have a better cache system?  I thought SCSI was good at
>   >>managing a data bus when multiple devices are attached.  If we are
>   >>only talking about a single drive, explain why SCSI is inherently
>   >>faster at managing data from a hard drive.

The Adaptec 1540-series use bus mastering.  This means that the CPU
doesn't sit waiting for data bytes, it can go off and do other
computing - if you have an advanced multi-tasking OS, that is.  DOS
just sits and waits anyway.

>
>   >IDE:  Integrated Device Electronics 
>   > currently the most common standard, and is mainly used for
>   > medium sized drives. Can have more than one hard drive.
>   > Asynchronous Transfer: ~5MB/s max.
>
>   Why don't you start with the spec-sheet of the ISA bus first?
>   You can quote SCSI specs till you're blue in the face, but if they
>   exceed the ISA bus capability, then what's the point?
>
>   Who says IDE is limited to 5 megs/sec?  What about VLB-IDE?  Does anyone
>   know how they perform?

Why don't you start with the spec-sheet of the ISA bus first? :-) IDE
was designed to plug into ISA virtually unaided - in essence, IDE *is*
ISA, on a ribbon cable.  Therefore it's specs are the same as ISA -
8MHz clock, 16 bit width, 5MB/sec.

This is why I've concluded that IDE on VL-bus is a waste of a fast
slot.  The card's job would to slow the VL-bus transactions to ISA
speed.  Heck, that's what ISA slots do - I'll just use one of those
instead.
-- 
Richard Krehbiel                                 richk@grebyn.com
OS/2 2.0 will do for me until AmigaDOS for the 386 comes along...
