Date   : Sun, 26 Nov 2006 22:23:00 +0100
From   : danielg@... (D.G. van der Pol)
Subject: Formatting a scsi harddisk for ADFS

I am trying to connect a scsi harddisk to my BBC computer. I build a  
sasi/scsi interface an exact copy of the Host adapter from the the  
Acorn Service Manual for the Winchester Discs.

Building it on stripboard was quite a challenge, but after debugging  
it all seems to work, electrically.
The Service Manual for Winchester Discs describes some tests which  
work out well.

I managed to 'initialize' my harddisk, with SuperForm but after that,  
ADFS still thinks I have a Bad Map.
I guess this is because ADFS does not take into account that the  
harddrive connected uses 512 bytes/block. It writes blind, without an  
error, but while reading, it gets something else back, than it expected.

My harddrive is a Seagate ST32171W, which has a "Selectable even byte  
sector sizes from 180 to 4,096 bytes/sector" So, it should be  
possible to reformat it with 256 byte blocks. But SuperForm does not  
send this specific request to the drive. It simply issues a Format  
Unit command, which leaves the blocksize at 512 bytes.
I know that I would not be able to use the entire harddisk, 512 Mb or  
even 256Mb would be more than sufficient.

I have looked through a few hundred messages in my list archive, but  
could not find any answer to my two questions:

- Does anybody has a formatting program that will send the required  
commands to any harddisk to select the 256 byte blocksize?

- Does anybody have, or is able to patch an ADFS rom which can use a  
harddrive with 512 bytes blocksize?

I know it should be possible to add the right commands to a program  
like SuperForm so it will set the right Mode Page before issueing a  
Format Unit command. Sadly I am not able to write anything like that.

Daniel