Date : Mon, 08 Feb 1999 11:46:19 -0000
From : "Fraser, Colin J" <Colin.Fraser@...>
Subject: Re: BBC hard drives
> -----Original Message-----
> From: Mark Usher [mailto:marku@...]
> Sent: 07 February 1999 00:11
> To: BBC MICRO Mailing List POSTINGS
> Subject: RE: [BBC-Micro] BBC hard drives
>
> > I'm considering trying to put a SCSI HDD onto the BBC's 1MHz port,
> > according to the instructions in the Harddrive-V1.2.zip
> file on the BBC
> > lives website. Has anyone any hints / recommendations they
> would make
> > before I start? I've already seen that the power connections to
> > the circuit
> > board given are inconsistent - perhaps there are other
> things of which I
> > should be aware?
>
> Yes. Using the circuit board "as is" will enable the
> connection of an SCSI
> hard drive, but it will not function 100% correctly. I am
> still unsure as to
> the reason why. The only way to make a hard drive work without any
> alterations to the design is to connect a MFM / RLL drive to
> the interface
> via an Adaptec 4000/4070 board or similar as described in the
> documents.
I did some work on the Beeb hard drive interface, but from a different
angle.
I built an interface board based on the host adapter board that doesn't have
that SASI bus, but instead has some latches, address decode logic and
another 1MHz bus interface.
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.
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...)
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.
Progress is slow however, as my spare time is limited...
Colin f
PS
Anyone have Hybrid Music 5000/4000/2000 manuals they might be able to copy ?
I only have the M500 manual, but have all the x000 software, keyboard etc.
Inside Hybrid's Music 5000 article at -
http://www.octavo.demon.co.uk/colinf/m5000/m5000.htm