Date   : Mon, 08 Feb 1999 13:55:02 +0100
From   : "Mark Usher" <marku@...>
Subject: Re: BBC hard drives

Hi

> I tested this board out connected to my Master as a host
> adapter, and a
> Model B on the other end with a bit of code to let me see
> what the Master is
> sending on the SASI bus. I got as far as seeing how the ADFS
> determines it
> has a functional host adapter connected to the 1MHz bus, and
> how it then
> looks to see if it can find any devices.
Wouldn't it have been easier to diassemble the ADFS rom to see how it checks
the 1MHz bus  ?

> The next step is to determine the format of the SCSI commands
> used - this
> should be similar to the SCSI 1 implementation (couldn't find
> anything about SASI...)
Yes the commands are pretty much the same. The problem about putting an SCSI
drive on the SASI adapter seems to be more one of timing rather than command
sets. I've not been able to solve it though :-(

> The reason I'm doing this is that I have good documentation on how to
> construct an IDE interface for an 8 bit microcontroller.
> Once I have sussed out the command set used by ADFS, I will build a
> stand-alone board with possibly an 8051 or AVR
> microcontroller to provide an
> IDE interface for the BBC that works with the standard ADFS.
Maybe a few of the people on the list can help you out with some more tech
info.
Definately a project that would benefit many. On the IDE side of things, I'm
not actually sure if it is possible to low level format an IDE drive to use
256bytes per sector.

> Progress is slow however, as my spare time is limited...
I know that feeling.

Alan Williams mailto:ajw@... has also been doing a little work
in this area. It could definately be beneficial to drop him a line as I'm
not sure that he is on this mail list or not.

Mark