Date   : Fri, 18 Jan 2008 14:33:40 +0000
From   : mike@... (Michael Howard)
Subject: Z80 CP/M Software Discs

Michael Howard wrote:
> 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.
>
>   
Appologies for following up my own post but the penny has begun to drop 
at last.

I got the Z80 out, tested and copied my set of discs using it and all 
worked perfectly, so the discs are good.

I have also imaged them using Johnathon Harston's 'DiskToImg' and 
written them back, successfully, to disk with 'ImgToDisk'. So goal achieved.

Thanks to everybody that helped.

Cheers,
Mike.

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