Date   : Mon, 05 Apr 2010 14:50:16 +0100
From   : mark@... (Mark Usher)
Subject: ADFS & 512 byte sectors

Yes, sorry, should have been more specific. I meant with hard drives, not
the floppies. 
I know using a hard drive on the 8bits required the ST506 to be formatted
with 256 bytes per sector, also the stacking filestores with their SCSI
drives.

If I skip a generation and look at the A4000, that uses a standard IDE drive
at 512 bytes per sector formatted with ADFS.
So was just wondering where in the OS history this change took place. 

-Mark


> -----Original Message-----
> From: bbc-micro-bounces+mark=bbcdocs.com@...
> [mailto:bbc-micro-bounces+mark=bbcdocs.com@...] On
> Behalf Of Rick Murray
> Sent: 05 April 2010 14:28
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] ADFS & 512 byte sectors
> 
> On 05/04/2010 02:22, Mark Usher wrote:
> 
> > Does anyone know at what stage did ADFS start using 512byte sectors,
> if
> > it ever did. I presume it was at one of the RISC OS stages, v3.xx
> > onwards,
> 
> I don't think they ever did.
> 
> 
> I am open to correction, but my brain says (for 3.5" floppies):
> 
>    ADFS S (160K)         - 256 byte sector
>    ADFS M (320K)         - 256 byte sector
>    ADFS L (640K)         - 256 byte sector
>    AFS0   (640K?)        - 256 byte sector
> 
>    ADFS D (800K) old map - 1024 byte sector
>    ADFS E (800K) new map - 1024 byte sector
>    ADFS other (HD, F...) - 1024 byte sector
> 
> Essentially, the 6502 based machines use a 256 byte sector, the ARM
> based machines use a 1024 byte sector. It's MS-DOS that uses 512 byte
> sectors. Dunno about Unixy formats, but those aren't natively supported
> by RISC OS.
> 
> 
>  > when Acorn started to integrate IDE interfaces in their machines.
> 
> This was with the introduction of the A4/A5000 when they moved from
> discrete logic and specific controllers (i.e. 6551 serial, logic
> parallel, 1770 FDC...) to a single ISA-ish combi-IO chip that did "all
> the usual".
> 
> This is also when the ARM range moved from SCSI and/or ST506 (both via
> expansion) to using IDE natively on-board.
> 
> 
> Best wishes,
> 
> Rick.
> 
> --
> Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
> BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
> E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...
> 
> 
> 
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