Date : Sun, 04 Sep 2011 22:10:23 +0200
From : vanekp@... (P. Van Ek)
Subject: Sometimes they come back... OSWORD &7F question
A good reference on the osword &7F is the Acorn Advanced Disk User Guide
which you can download from
http://www.bbcdocs.com/filebase/hardware/AdvDiskUG.pdf
I think (if my memory serves me correctly) it only covers for the 8271 DFS
not sure if there were references in there for the 1770 controller.
Peter.
----- Original Message -----
From: "Carlo" <conca@...>
To: <bbc-micro@...>
Sent: Sunday, September 04, 2011 19:37
Subject: [BBC-Micro] 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.
>
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