Another disk imaging project

Jim Battle frustum at pacbell.net
Wed Aug 3 08:05:21 CDT 2005


Dave Dunfield wrote:

> Hi Guys,
> 
> I'm really getting fed-up with the limitations of the PC floppy disk
> controller.
> 
> Here's another idea I've had on the back-burner for quite some time, I've
> mentioned to a couple of you during private correspondance, but here it is
> for open discussion.
> 
> The idea is to make a small single-board computer with a microcontroller,
> a WD2793 or similar floppy disk controller, enough memory to buffer a
> few tracks, and a high-speed serial port for communication with the PC.
> The board would have connectors for 5.25"/3" drives and 8" drives, and
> would properly interface to all drive types.
> 
> Firmware would be developed to provide read/format/write/analysis
> capabilities around the more powerful WD chip. Images would be transferred
> via the serial connection to and from the PC. This should allow us to
> archive soft-sector formats that are not compatible with the PC, and also
> to perform these functions under virtually any PC environment.
> 
> I just haven't had time to design and build the board ... anyone else
> interested in working together on such a project?

Dave, why not just write software for a catweasel card?  I realize that the 
catweasel's FPGA has been programmed with a bitmap made from closed-source RTL, 
but is that a serious impedement?  When the day comes that the catweasel is no 
longer supported/sold, it would be possible to at that point design another one. 
  People here have daydreamed reinventing the catweasel with only TTL parts so 
prevent lock-in; that is fine, but nobody has done anything about it (the 
daydreaming is the easy part, by a factor of 1000).  The catweasel is here and 
real, and at $100, it is price reasonably.

At that last statement I know one or more people are going to say: rubbish, I 
have the parts here in my junk bin that I could put together what I want for 
free.  Well, what you'd have would be a pile parts that took at least ten hours 
of design time, and you'd still need to spend much more than that writing 
software before coming up to speed with the catweasel.  Sure, not everybody will 
be able/willing to spend $100 for something like this, but that is far less than 
the number of people who would be put off by having to build their own hardware.

The one thing that I feel is missing from the catweasel is a 50-pin header for 
connecting to standard 8" floppies.  Another minor gripe is that each of the 
versions of the catweasel (now four) tries to be register compatible with 
previous versions while adding new functionality.  It has lead to some arcane 
programming requirements, which is sad: a very thin API to hide version changes 
would have made things much simpler.

Finally, is the WD2793 able to read northstar horizon floppy disks?  If not, 
then a WD2793-based solution is not general enough.




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