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From: apratt@atari.UUCP (Allan Pratt)
Newsgroups: comp.sys.atari.st,comp.sys.atari.st.tech
Subject: Re: Weird TT hard disk thingy
Message-ID: <2930@atari.UUCP>
Date: 6 May 91 21:36:00 GMT
References: <2917@atari.UUCP> <1991May1.143101.3904@mailer.cc.fsu.edu> <2925@atari.UUCP> <1991May5.123222.14113@mailer.cc.fsu.edu>
Organization: Atari Corp., Sunnyvale CA
Lines: 41

boyd@nu.cs.fsu.edu (Mickey Boyd) writes:
>    A working ST system:  Mega4, laser printer, Supra Hard disk.  The SCSI 
>        drive contained within the Supra is set to SCSI id 1.  The ST does 
>        not mind this at all.  Everything works.

I conclude that the Supra controller responds on the ACSI bus using the
unit number of the SCSI drive connected to it; see below.

>    A TT system is purchased.
>    The DMA cable connecting the Supra to the working ST setup is 
>        disconnected, and attached to the ASCI DMA port on the TT.  
>    The computer is booted.
>    The Supra is invisible to the TT desktop, for no apparent reason.  
>        Nothing is stated in the manual.  No error messages from the 
>	 HDX software. 

I stand corrected.  I should have said, "A working system WITH ATARI
DRIVERS will work when plugged into a TT."  What is happening here is that
on the ST, you are booting with Supra's driver off the Supra hard disk, and
on the TT you are booting with Atari's driver on the TT's internal hard
disk.

Supra's driver will find ACSI units which are not connected in consecutive
order starting with zero, and Atari's driver won't.

The same thing would happen if you connected an ACSI drive, as ACSI unit
zero, HINSTALLED with Atari's driver, to the ST: you would get Atari's
driver, not Supra's.  (Of course, since you now have consecutive ACSI unit
numbers starting from zero, your Supra would be found; if the Supra were
unit 2, it would not be.)

There is another problem which has been called to my attention, and which
is covered by the same "Atari drivers" caveat: Supra uses one trick to get
more than four partitions per drive, and Atari uses another. If you have a
drive partitioned with Supra's trick, and you connected it to a TT (or any
machine running an Atari driver) the partitions after the fourth one will
not be accessible.  Again, it's a question of using non-Atari drivers.

============================================
Opinions expressed above do not necessarily	-- Allan Pratt, Atari Corp.
reflect those of Atari Corp. or anyone else.	  ...ames!atari!apratt