Date   : Wed, 12 Oct 2005 22:12:02 +0100
From   : "Ian Wolstenholme" <BBCMailingList@...>
Subject: Re: Programming the 8271 and 1770 FDC's from BASIC

I don't think it is too difficult; you would use the OSWORD calls to
communicate with the floppy disc controller.  "Officially" OSWORD &72 is
the ADFS one and &7F is the DFS one but I suspect that this probably
has more to do with whether the controller is being used in FM or MFM
mode as far as the 1770 is concerned.  Pages J.11-12 to J.11.15 of
the Master Reference Manual part one set out the format of the OSWORD
parameter block.

You would need the 8271 and 1770 data sheets (available somewhere on
the internet) for details of the commands available and the parameters they
take.

It might also be worth having a look at some of the BBC disc copiers
(my favourite being Ripoff IX) for details of how they access usual disc
formats.

Best wishes,



Ian

----- Original Message -----
From: Jules Richardson
To:  bbc-micro@...
Sent: Wed, 12 Oct 2005 19:00:19 +0100
Subject: [BBC-Micro] Programming the 8271 and 1770 FDC's from BASIC


Out of interest, how easy is this?

I'm idly thinking that having a BBC hooked up to the PC via a serial 
link and running some sort of "Son of Xfer" software would be handy in 
making/restoring disk images for some of the other non-Acorn hardware 
that I use. The BBC's probably got the best BASIC in a machine of that 
timeframe.

Obviously I need it to work with oddball sectors per track - tracks I 
expect will always be 40 or 80, unless I hook up an 8" drive to the 
beeb, at which point 77 might be useful too.

I *think* xfer makes use of fairly high-level ROM routines to read/write 
  at the track level though (not studied the code yet), whereas I'd need 
to presumably talk to the disk controller chip direct.

Anyone out there have any useful notes or pointers to info? May well be 
a non-viable project for all sorts of reasons, but it was just an idle 
thought this morning...

cheers

Jules