Date   : Sat, 16 Jul 2005 15:04:20 +0100
From   : "BeebMaster" <beebmaster@...>
Subject: Re: floppy discs

Yes, it just crashes if you run it on the Master, obviously due to
different commands in the 177x controller.  It wouldn't even work in
8271 emulation mode (ie. Z-BREAK).

I think similar difficulties occur when running the Level II Econet disc
initialiser on a 1770 system.

Best wishes,


Ian

----- Original Message -----
From: Andrew Benham
To:  BeebMaster <beebmaster@...>
Cc:   bbc-micro@...
Sent: Sat, 16 Jul 2005 12:45:01 +0100
Subject: Re: [BBC-Micro] floppy discs

BeebMaster wrote:

> By the way, it doesn't work in 1770 DFS (I think it is a different format
> control code for the 1770 series).

The 8271 floppy disk controller has a "format track" command, so the
software to format the disk has to call this command 40 or 80 times.

The 1770 floppy disk controller doesn't have this command. Instead
it has a "write raw track" command - the software to format the disk
has to build (in memory) a template copy of a blank formatted track.

The OSWORD &7F command is designed around the 8271 commands - in the
Acorn 1770 DFS the appropriate commands are translated to do the right
thing on a 1770 FDC.
Off the top of my head I can't remember if the Acorn 1770 DFS's OSWORD
&7F handles the "format track" command correctly for the 1770 FDC.

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"