Re: CBM-900 floppy disk format/encoding

From: Uffe Jakobsen <uffe_at_uffe.org>
Date: Mon, 09 Jan 2012 00:41:28 +0100
Message-ID: <4F0A29A8.8000305@uffe.org>
Hi Martin,

On 2012-01-08 13:48, Hoffmann-Vetter, Martin wrote:
>
>> On the other hand, I never tried to read a c900 disk in a 8250 or
>> SFD1001.
>
> The other question is, can a 8250 (or sfd-1001) modified to read c900 disks?
>

Our C900 hobby project have been stalled for a while now - mostly 
because og Xmas season and for my part $work activities - we hope to 
pick up the project again soon.

For now I can tell that it seems we have been fooled be the 
documentation (maybe) at the moment we are investigating *IF* the drive 
in our CBM900 prototype is a 100TPI drive as the documentation states.

Right now much points in the direction that its an 96TPI drive - it is 
difficult to say if the drive have been there from the beginning or if 
it has been switched at some point in time - its a prototype that used 
to belong to an engineering company - so anything is possible.

> When Uffe dump the roms from the real c900, we can lock at the rom for the
> disc controller and compare with the 8250 roms.
>

We have dumped the roms - but I cannot get to them right now
Only having quickly looked contents at the rom - my "feeling" is that it 
is a whole new rom.

Until we gain momemtum with our project the only thing that I can give 
you is this:

Here is a link to a photo gallery (53 photos) of the CBM 900 PCB and its 
components in our prototype:

http://www.datamuseum.dk/foto/20111117


/Uffe :-)









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Received on 2012-01-09 00:00:17

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