Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!unisoft!hoptoad!wet!pk
From: pk@wet.UUCP (Philip King)
Newsgroups: comp.sys.amiga.hardware
Subject: Re: SCSI-1 vs. SCSI-2
Message-ID: <2242@wet.UUCP>
Date: 22 Mar 91 01:25:11 GMT
References: <2216@wet.UUCP> <19941@cbmvax.commodore.com> <19967@cbmvax.commodore.com>
Organization: Wetware Diversions, San Francisco
Lines: 36

In article <19967@cbmvax.commodore.com> jesup@cbmvax.commodore.com (Randell Jesup) writes:
>In article <19941@cbmvax.commodore.com> daveh@cbmvax.commodore.com (Dave Haynie) writes:
>>In article <2216@wet.UUCP> pk@wet.UUCP (Philip King) writes:
>>
>>>Dave, does this mean that Amiga hard disk controllers support synchronous
>>>transfers?  I don't think I've ever seen any of the host adaptor 
>>>manufacturers claim that.
>>
>>Sure do.  Apparently, though, the our host adaptors won't normally request
>>synchronous transfers.  Some drives lock up, or otherwise misbehave, if you
>>ask for synchronous transfers.
>
>	Yup.  We will do synchronous if the drive requests it (quantums can
>be told to request it: mode select page 55, byte 2, bits 4 and 5).  There may
>be a battmem bit for it; ask steve.  Some older scsi drive (guess who) will
>crash and take the bus down with them if asked to do synchronous.

Randall, perchance were you referring to ***gate when you alluded to some 
drives taking the bus down if you requested synchronous?  I have an Imprimis/
Seagate ST-1239N, which is a 200M 3.5" drive that supports synchronous transfer
(there's a jumper you add).  I presume that if ***gate was the party in
question, then my drive should be fine, since it's really originally a
CDC/Imprimis piece?

Does anyone else know if other host adaptors support Synchronous?  I  
am using an ICD Advantage 2000, which is otherwise a very fast host adaptor.  

I also wondered if anyone else had any more specific information on how
to activate my drives read-ahead cache, with the 'mode select' command
Lee Erickson and Dave were referring to earlier.  Is there a program that    
allows me issue these commands?
 
 
				Philip King
				pk@wet.uucp
				{ucsfcca,claris,hoptoad}!wet!pk