Date   : Thu, 17 Jan 2008 13:06:08 +0000
From   : mike@... (Michael Howard)
Subject: Z80 CP/M Software Discs

Jonathan Graham Harston wrote:
>> Message-ID: <47888A1D.4040209@...>
>>     
>  
> Michael Howard wrote:
>   
>> Am I correct in believing that the set of 7 discs for the Z80
>> co-processor are simply 80 track DFS discs each containing a CP?M 'image'?
>>     
>  
> Almost. They are double-sided 80 track DFS disks, on side 0 is a
> dummy file called CPMDISC that occupies the whole of side 0, but
> does not contain the whole of the CPM filesystem.
>  
> The CPM filesystem starts at track 0 sector 0 (ie, the DFS
> catalogue). Part of the CPM filesystem has some space reserved in
> it to contain the DFS catalogue. CPM doesn't look fo the CPMDISC
> file, it accesses sectors directly.
>  
> See http://mdfs.net/Docs/Comp/Disk/Format
>  
>   
Uhm! I'm getting confused now, which you might say is not unusual for me.

The reason I asked the question originally is that I'm in the process of 
archiving my floppies and the Z80 CP/M disks are giving me problems. 
These discs were not mine from scratch, so I don't know their history.

Disc 1, is recognised by my BBC (and Acorn with !DFSReader) as a DFS 
disc, the remaining 6 discs are not recognised either natively (no 
surprise) or with  !DFSReader. If, however I use !CPMFS, they are all 
recognised and I can see (catalogue) the contents.

Steve Bass stated in an earlier reply that only discc 1 was DFS, the 
remainder are Acorn CP/M format which would explain why they are not 
recognised.

Having said that, Omniflop is steadfastly refusing to read them if I 
tell it they are Acorn CP/M format (hence my confusion). My aim is just 
to get reliable images that I can write back if need be. I did suspect 
the discs were at fault initially, but as I say, I can read them using 
CPMFS.

I've seen the images at http://mdfs.net/Mirror/Image/AcornCPM/ and 
thought I'd try writing these to disc with Omniflop but no joy, though I 
think I have only tried to write to Acorn CP/M format discs with the 
CPM2 image. Could somebody inform me of the best way to get these to disk?

I will get the Z80 out of the loft this evening and try booting 
everything up natively to double check the discs.

Cheers,
Mike.

-- 
Michael Howard         mike at dewberryfields dot co dot uk
Lancashire
England