Date   : Sun, 17 Apr 2005 15:13:13 +0100
From   : Richard Gellman <splodge@...>
Subject: Re: KeyBoard, Winchester Hard Drive


Jules Richardson wrote:

>Actually, the Acorn SCSI interface is the only really difficult bit to
>get hold of - I've only seen one in the last few years. But I usually
>pick up 4 or 5 ST506-interface drives a month, and come across SCSI-
>  
>
>>ST506 bridge boards every few weeks. There's a lot still about, lurking
>>    
>>
>in cupboards...
>
>  
>
Just to confirm, when I refer to "Acorn SCSI Interface board" I mean the 
board that sits between the 1Mhz bus and the SCSI<->Winchester Board.

>Can't remember now, but do the various SCSI->ST506 boards support a
>standard "format unit" command, or was this specific (via vendor unique
>extensions) to each type of bridge board? If the latter then the Acorn
>formatters won't work except with the right kind of bridge board...
>  
>
The SCSI standard specifies a "Format Unit" command as well as a few 
lower-level format commands (taking into account sector size, etc).  The 
SCSI<->ST506 boards accepted most varieties, as well as the query unit 
command used to determine drive geometry. That was stored on the disc 
itself in an "out of bounds" region, requiring specially prepared ST506 
drives (or at least formatted using said board and manually specifying 
geometry) so that the board knows how to translate.

>As for SCSI drives capable of 256 bytes / sector, it'd be interesting
>for someone to do some experimenting. It wouldn't surprise me if none of
>the 3.5" SCSI drives support it though :-(
>  
>
The newer ones probably won't, but some of the older drives (I would 
expect my Seagate 500Mb to do it) will, as they were made to satisfy a 
wide range of computers, some using 512 bytes, some using 256.

-- Richard