Path: utzoo!utgpu!watserv1!watmath!att!dptg!lzsc!hcj
From: hcj@lzsc.ATT.COM (HC Johnson)
Newsgroups: comp.sys.atari.st
Subject: Re: READING HD HYSICAL SECTORS
Message-ID: <1355@lzsc.ATT.COM>
Date: 2 Mar 90 19:56:18 GMT
References: <16000016@ux1.cso.uiuc.edu>
Organization: AT&T BL Middletown/Lincroft NJ USA
Lines: 26

In article <16000016@ux1.cso.uiuc.edu>, cs325ec@ux1.cso.uiuc.edu writes:
> 
> 
> 	Someone from the Netherlands responded to my post about
> 	reading physical sectors from a Hard Disk.  His code was
> 	accurate and worked... Setting bit 3 in the rwflag enabled
> 	physical sectors to be read... but...  Secno however,
> 	is an int and can not be higher than 32767 or 65535 if 
> 	Rwabs can handle unsigned, so how do I read sectors
> 	higher than those?

The real answer is you dont.  And this is why.
The use of bit 3 is/was really to get to sector 0 and maybe 1 and 2.
(1 and 2 might contain a list of bad blocks).  After this, very limited
area, it is expected that partitions will cover the physical disk.

TOS partitions can then be accessed by drive and offset.

What about Spectre and Minix partitions?  Then you need your OWN driver
that will access sectors as a long absolute value.  Thats what Spectre
and Minix do.

Howard C. Johnson
ATT Bell Labs
att!lzsc!hcj
hcj@lzsc.att.com