[ On Tue, March 10, 1998 at 15:56:22 (-0600), mill0440 wrote: ]
> Subject: Re: Hard drive
>
> On Tue, 10 Mar 1998, Claude Foley wrote:
> >
> >I'm planning to buy a hard drive for my Sun 3/60,
> >
> >What is the best buy for a 2 Gig Scsi hard drive that will work on my Sun.
> 
> Not sure. 

Any SCSI-2 FAST drive should work A-OK

> >What is the difference between ULTRA SCSI and ULTRA WIDE SCSI.
> 
> ultra-wide uses 16 bits to transfer data.

Actually "ultra" and "wide" are two different things.

Fast SCSI allows faster timing on the bus. ( 10MHz instead of 5MHz )
Ultra (or Fast20) SCSI allows up to 20MHz signals on the bus.  Ultra2
(or Fast40) SCSI allows up to 40MHz signals on the bus.

Wide SCSI uses an extra cable (or a 68 pin P cable) to send the data in
16 or 32 bit wide words (instead of 8-bit words for all non-wide SCSI).
(Note that 80-pin connectors are found on "SCA" drives, normally used in
RAID arrays and sometimes in workstations.  SCA Stands for "Single
Connector Attachment". It combines WIDE SCSI signals, power connections
and ID selector connections onto one connector.  Inexpensive adapters
that present normal 68 (or even 50) pin bus and power connectors, and ID
jumpers.)

Read the FAQ for more SCSI enlightenment:

	http://www.ultranet.com/~gfield/gary/scsifaq.html

You might also find this companion guide handy:

	http://www.ultranet.com/~gfield/gary/scsigame.txt

>  Your sun can only handle 8
> bits, so buying ultra-wide is a waste of money.

Yes and no.  Depends on what you do with the drive afterwards -- it
should have a much longer lifetime than even a well cared for Sun-3 and
a wide drive will be much more useful on a newer machine in the future.
Retail prices on wide drives are not much higher for some categories
around here....

>  Also you would need some
> fancy adaptors to use wide-scsi on your sun.

They're not all that fancy -- I've seen them in most computer parts
retail stores around here for about $30-$50.

The biggest problem with Sun3 SCSI is that it commonly uses the DDB-50
connector (like a DB-25 but with 50 pins).  Adapter cables are
available, but new they cost $50 or more.  Used ones might be found for
much less though.  I've even found DDB-50 to HD-50 cables!  ;-)

> Ultra scsi is much faster then your sun can handle, but things will
> gracefully step down.  What this means to you if a drive has a slower
> transfer speed, but is otherwise as reliable and fast it is still good
> enough.  You probably won't be able to find drives like that though.
> 
> Basicly scsi has passed over you sun, while things will be avaibal for a
> while that still supports it everything is going to wide-scsi, and you
> will never be able to take advantage of wide scsi.  Don't worry about it
> though, there are options.

SCSI has most definitely not passed by the Sun-3s!  ;-)
(Unless you have only an ancient Sun-2 (SCSI-1) VME host adapter....)

They work OK and NetBSD will speak the full SCSI-2 command set.

Yes, they have only normal 8-bit buses, but that's fine for any
application they're rated for anyway.  Many of the faster drives have
added benefit because of their much lower average access times, and with
some cache they are faster still, even on a sun3.

-- 
							Greg A. Woods

+1 416 443-1734			VE3TCP			robohack!woods
Planix, Inc. <woods@planix.com>; Secrets Of The Weird <woods@weird.com>