Sources for Disk Controllers

[Julian]

I'm trying to maintain the excuse of keeping my trusty D64 on the basis that if I can get a disk controller I can actually do some practical things with it but obtaining a disk controller is proving entertaining (if I can abuse the word in this way).
Having sat on ebay for months I've only seen a few controllers (dragon dos) come up and they went for frankly stupid money in the end.

So what are the alternatives? I've looked at the diagrams for the DOS controller and it appears simple enough and the components are largely still available (although I suspect the internals have changed) but what I did notice is that there are a couple of trimmers to fine tune the board and not surprisingly no information on what the required corrections might be. We have the code for the eprom so what would be the problem with recreating a board - other than the fine tuning? Would it be easier to adapt a controller from another source?

I'd like to point out that my electronic skills are well and truly stuck in the 80s and at only a modest level - this could actually be an advantage in some ways.

[tjewell]

Hi,

There's a discussion going on on the Dragon User Yahoo Group about using Cloud9's IDE controller carts on a Dragon - take a look at this:

http://www.frontiernet.net/~mmarlette/C ... CFIDE.html

And this thread:

http://finance.groups.yahoo.com/group/d ... ssage/1910

Not entirely sure if you can get access if you're not a member of this group.

Cheers, Tony.

[robcfg]

I know of some people in Spain working on cloning DragonDos cartridges using original components, I'll keep you up to date when there's some progress.

Maybe a fpga solution would be interesting.

[admin]

Should not be too hard to produce all the components needed are still available...

The trimmers are for the WD2797 FDC and only need to be set once using an oscilloscope - The details can be found on the WD2797 datasheet (although if I recall a conversation with Prime - these have an error but he has some figures that have worked). Prime has also prototyped an SD card interface that allows native loading of .CAS files which may also be of interest - maybe it might also be possible to expand this to emulate the WD2797 and mount DSK images or something...

The CoCo IDE stuff should work if somebody re-writes the code to fit the Dragon....

Personally I use a DOS controller with the HxC floppy emulator and just mount disk images these days, but mostly I now use the trial prototype from Prime to mount CAS files to play games

[Julian]

More perversely (being quite ignorant of the internal workings of the current DOS variants) - what would it take to create an IDE interface?

It's been a mighty long time since I studied operating systems and the only big stumbling blocks I can think of are the block/side/segment addressing basics and potentially, size of the file address table and possibly the raw communication speed. IDE controllers would be pretty easy to get hold of in comparison with a FDC and most people with an interest in computer hardware I know have got a least one old IDE harddrive lying around of very modest capacity (even a small 20Mb HDD would feel immense).

[robcfg]

Yes, it would be nice. And given the experience on other platforms, the hardware may not be so difficult to design and build.

I think the problem here is software. It's not only providing access to raw sectors, it's about providing image mounting and other capabilities, which is a heavier task.