P112

[David Griffith]

On Sun, 8 Apr 2018, Bill Gunshannon via cctalk wrote:

> I have no idea of the format.  I got the images and rawrite.exe and
> told the computer to make them.  They were unusable when I used
> a USB External floppy but worked fine when I used a real internal
> floppy.
>
> I need to get the systems running before I start playing with reading
> and writing weird formats.  But that is coming.
>
> As a side note, I did get the system to boot and run from my floppy
> emulator with a USB stick.  Have to boot twice.  First time you get
> the unrecognized format error second time boots fine.  Interesting.
> Good to know for when I am testing on other systems as well.
>
> Small steps, but advancing, just the same.
>
> bill

I seem to recall using a USB floppy drive to make P112 disks, but I also 
did it using a Linux machine with the dd command.  The rawrite.exe program 
is very old and I suspect it and modern Windows systems don't see 
eye-to-eye anymore.

The format is described in the cpmtools diskdefs file.  Below are the 
entries that seem most relevant to the P112.

diskdef p112
   seclen 512
   tracks 160
   sectrk 18
   blocksize 2048
   maxdir 256
   skew 1
   boottrk 2
   os 3
end

diskdef p112-old
   seclen 512
   tracks 160
   sectrk 18
   blocksize 2048
   maxdir 128
   skew 1
   boottrk 1
   os 3
end

diskdef gide-cfa
   seclen 512
   tracks 1000
   sectrk 16
   blocksize 4096
   maxdir 1024
   skew 0
   boottrk 2
   os 3
end

diskdef gide-cfb
   seclen 512
   tracks 1000
   sectrk 16
   blocksize 4096
   maxdir 1024
   skew 0
   boottrk 0
# Start of second partition
   offset 1000trk
   os 3
end


-- 
David Griffith
dave at 661.org

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