Date   : Thu, 08 Jan 2004 21:37:18 +0000
From   : Mike Tomlinson <mike@...>
Subject: Re: IDE Interface for BBC

In article <6548626.1073562715248.JavaMail.www@...>, c.j.thornley@
coolrose.fsnet.co.uk writes

>    I found an existing circuit for an IDE interface for the bbc micro. 
>    Found @ http://www.chrisward.uklinux.net/6502/circuit.shtml=A0and 
>    picture @ http://www.chrisward.uklinux.net/6502/schematics/ide.png

It's not specifically for the Beeb, and the circuit as shown would need
quite some modification to make it work on a Beeb.

>    This might alleviate problems with 16bit adressing on an 8bit 
>    system.

It works by clocking the 16 bits of data from the drive into two 74LS573
latches, then transferring the contents of those in two chunks onto the
6502's 8-bit data bus.

>    What capcity harddrive will the interface on the list support as 
>    harddrive less that 40Gb are difficult to source at shop and some 
>    machine can have a limt at 32GB and 137GB as the bit addressing 
>    changes.

JGH's suggestion was to modify ADFS to directly work with a simple IDE
interface, thus it's not a question of the PC's 32 and 137 (actually,
it's 127) GB limits, but the maximum drive size that ADFS can address.
Anyone know?

>    Is it best to have an acorn format or a PC or NTFS based one to 
>    allow easy transfer and preping of the drive.

I'd prefer to stick with Acorn format and make it as compatible as
possible with the Acorn Winchesters and ADFS.  It can then be prepped
with SuperForm.  Using a PC format would require a new FS ROM to be
written, and assuming it fitted into 16k, might attract the attention of
Microsoft's landsharks.  After all, if they're now demanding money for
licensing the FAT filesystem...

>    Is the page level altered significantly

With ADFS on the model B, it's raised to &1D00 IIRC.

> and will it be easy to 
>    transfer file from one filesystem to another.

That's what the CopyFiles program is for on the Model B.  On the Master,
you could do it by directing * commands at a particular ROM:

*-disc-Load :0.$.Chuckie 2000
*-adfs-Save :4.$.Games.Chuckie 2000+length 

etc.

Mike

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