Path: utzoo!attcan!uunet!snorkelwacker!usc!ucla-cs!rutgers!cbmvax!steveb
From: steveb@cbmvax.commodore.com (Steve Beats)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: Sync. SCSI drives for A3000
Keywords: Quantums worth it?
Message-ID: <13398@cbmvax.commodore.com>
Date: 24 Jul 90 10:05:28 GMT
References: <2036@esunix.UUCP>
Reply-To: steveb@cbmvax (Steve Beats)
Organization: Commodore, West Chester, PA
Lines: 32

In article <2036@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes:
>My A3000 should be here within a few days, and I'm thinking about
>upgrading it to a synchronous SCSI drive since the A3000 controller
>supports synchronous SCSI.
>
>A few questions:
>
>1) What drives are known to work? If I understand correctly, the
>"smaller" Quantum drives (40, 80, and 105 meg) do not support synchronous
>mode, but the larger ones (120, 170, and 210 meg) do. Is this correct?
>Are there other 3.5" synchronous SCSI drives worth looking at?

Quantums and CDC Wren x drives work well in Synchronous mode, as do the larger
Micropolis drives.  I haven`t tried any others.  BTW.  All Quantum drives
support Synchronous mode.

>2) What kind of transfer rate can I expect with a synchronous drive?
>Over 1M/sec, close to 2M/sec?
>
>3) Has anyone actually done this? What do you think of it? Is it worth
>it?

To answer both questions:  No, for a single drive you will not notice ANY
significant speedup.  The bits are not going to come off the platter at
more than 1.25 Mb/s!  In the single drive situation you will gain a little
system performance because the DMA chip will not hog the bus for so long
when it bursts blocks of data to/from RAM.  The only time sync xfer gains
you anything is if you are using more than one drive simultaneously, in
this case, the total bandwidth of all drives added together can approach
4Mb/s though individual drives will not exceed 1.25Mb/s.

	Steve