Date   : Sun, 04 Sep 2011 19:37:12 +0200
From   : conca@... (Carlo)
Subject: Sometimes they come back... OSWORD &7F question

Hello group,

I'm Carlo from Italy, proud owner of an Olivetti Prodest PC128S, aka a relabeled
BBC Master Compact.

Some of you will perhaps remember me, I've been a member of this list for
several years before unsubscribing, some years ago, due to a chronic lack
of time.
For the same reason I never completed the PC128S emulator I started coding
more than 10 years ago, which to my amazement is still online at The BBC Lives!

Not that I have plenty of time now, but I recently felt the urge to take
my old computer out of the mothballs and play around with it again. It still
works perfectly and now here I am with a tech question.

One thing that I've never ever been able to do is reading and writing raw
floppy disc tracks.
BeebWiki says that OSWORD &7F should be able to do just that with commands
&E0 and &F0, provided a 1770 DFS is used:

http://beebwiki.mdfs.net/OSWORD_&7F

(By the way, I discovered a mistake on this page: the Command and No. of
Parameters bytes (bytes 5 & 6 of the control block) are swapped.)

So I wrote a very simple program and tried it with various versions of the
1770 DFS with the OSWORD &7F patch for accessing double density discs.
The program is as follows:

    10?&3000=&38
    20!&3001=&4000
    30?&3005=1
    40?&3006=&E0
    50?&3007 
    55!&3008=0
    56!&300C=0
    60P%=&3010
    70[
    80LDA #&7F
    90LDX #&0
   100LDY #&30
   110JSR&FFF1
   120RTS
   130]
   140CALL&3010
   150PRINT?&3008

It simply sets up the control block and calls OSWORD &7F, then displays the
result byte. No matter what version of DFS I use, the disc drive never lights
up and the result byte is always &FE.
I even tried other commands apart from read track, but the result is always
the same. What am I doing wrong?

I tried to tackle the problem from another direction. I learned that the 
Solidisk DFS has * commands to read and write RAW tracks; the problem is
that Solidisk DFS seems to work only with the Solidisk add-on board, which
is wired differently from the WD177x controller built into the BBC Master.
Does anyone have a modified Solidisk DFS that works with Master hardware?
Or any other solution for raw disc track I/O?

Thanks in advance,
Carlo.