Another disk imaging project

[Jim Battle]

Dave Dunfield wrote:

>>>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.
> 
> 
>>Dave, why not just write software for a catweasel card? 
...
>>When the day comes that the catweasel is no longer supported/sold, it would be
>>possible to at that point design another one.
> 
> 
> Will it? Or will nobody bother as it's a tough job.
> Will it be 100% compatible, or will we find that disks that were created with
> this at-least partially proprietary system will be "lost" if the system cannot
> be made to work?

Most of the catweasel complexity (which is all buried in the FPGA) comes from 
supporting C64 sound chips, timers, joystick ports, and other stuff.  I get the 
impression that for many of the people who use this, it isn't an archiving tool 
-- they plug it into their amiga or PC, install the C64 software, and then just 
use their machines like a native C64.

The complexity of the formats that people create for various disk images is 
independent of the complexity of the hardware.  Why hasn't somebody done an open 
catweasel?  I think part of the issue is that for the people who would be 
interested in it, $100 isn't that off-putting.  If the catweasel developer lost 
interest (he has been supporting it through four versions for, how long? 10 
years? so far), then there would be a void that makes it more attractive to come 
up with another solution.

...
> Is the cat software open-source, are the internal and storage formats fully
> documented - one big thing about the work that I have been doing is to make
> sure that people in the future can access the data from the images so that
> they can find "other means" of regenerating the disk if necessary - even if
> that regenerated disk is just a different format image for a simulator.

The software is open source.  The people (one actually) who sell don't really 
develop the software.  Other enthusiasts write the code to varying levels of 
support.  The format used for a particular format is a question independent of 
the catweasel card.

Tim Mann has written code to read/write TRS-80 and RX-somethingorother format 
disks to DMK format.  The source is online.  I've written code for PTDOS and the 
source is available, although I doubt that anybody but me has ever used it (now 
there is a test case that would give your disk archiver a challenge).  I have 
more than 100 compucolor disks that I intend to archive, and that is guaranteed 
to not be compatable with your program either.  I know the C64 linux drivers are 
open source.

The only thing closed is the RTL used to generate the FPGA bitmap.

>>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.
> 
> 
> On this point I disagree - the board I am thinking of would be very simple,
> perhaps a dozen DIP chips - easy to build. I think a lot of the people on this
> list would gladly take an evening or two to build one - also if it were to be
> done, printed circuit boards, and even finished/tested boards could be made
> available at low cost (like the cat), but unlike the cat, fully documented and
> you can build it yourself if you like. It would not be "owned" or controlled by
> anyone.

I still stand by my bald assertion that more people would be put off by having 
to build it themselves than those who would be put off by the $100.  Also, for 
your $100 you get a professionally made board.  Many of the home built cards, 
even if only a dozen chips, might end up flakey and frustrating for the builders.

>>The one thing that I feel is missing from the catweasel is a 50-pin header for 
>>connecting to standard 8" floppies.
> 
> 
> A grave omission for something thats supposed to archive non-PC-standard disks.

A hassle for sure, but certainly a lot less than wirewrapping an assortment of 
TTL parts PLUS the 34/50 pin headers.

>>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.
> 
> 
> But would have tied the thing to one particular development environment (Here's
> you VisualC++ library - have a nice day). The best solution is a fully open and
> documented description of the hardware and lots of sample code.

That is a strawman -- it is possible to write a C library that is tied to a 
particular environment, but that is self-defeating.  People write portable C 
libraries all the time.

>>Finally, is the WD2793 able to read northstar horizon floppy disks?  If not, 
>>then a WD2793-based solution is not general enough.
> 
> As noted in the original message, it would be soft-sector only - the idea is to
> make a simple/cheap alternative to the limitations of the PC controller...

*some* of the limitations

> Still deciding if it's worth it - I'll record your "NO" vote.

Dave, I applaud you taking on the archiving problem.  Teledisk has been used so 
long simply because there is no good free alternative.  Even with the 
shortcomings of the 765, DiskImage is a good replacement for teledisk in that it 
is a software-only solution for the most common controller on the planet.  I 
think the next step after that requires hardware, and so why stop at a partial 
solution?

Personally, I hope to get around to getting my catweasel IV set up soon.  If the 
ImageDisk format is flexible enough, I'd be happy to write catweasel software 
that can read/write the formats I care about to ImageDisk foramt.  I strongly 
suspect that it isn't flexible enough to represent the PTDOS format, which is 
the format that I've already made up my own disk image foramt for since it is so 
unusual.