USB Universal Floppy Disk controller

[9000 VAX]

On Mon, 14 Mar 2005 20:51:10 +0000, Jules Richardson 
> 
> What about cost? (irrespective of how the device physically connects to
> the host machine)
> 
> I forsee four goals to make it useful:
> 
>   o  Cheap
>   o  Simple to build by anyone with a few electronics skills.
>   o  Open 'source' (all schematics etc. available)
>   o  Easy / quick connectivity
> 
> Catweasel seems to lose out on 1, 3, and 4 - and 2 isn't relevant in its
> case. Can't comment on how nice its software API is as I haven't looked
> at it yet, but doubtless a bunch of us on this list could come up with
> something that'd cater for all tastes (plus the really low-level
> software would all be open source anyway!)
> 
> Personally I'm not a fan of a USB version though; I'd rather have
> parallel as pretty much any machine has a parallel port - USB limits me
> to newer PCs and Macs (plus software interfacing *might* be harder).
> 
> Priorities seem to me to be (highest first):
> 
>   o  Reading disks
>   o  Writing back a disk image
>   o  Decoding disk data on host machine
>   o  Modifying disk data on host machine, re-encoding back to floppy
> 
> Happily, that's probably order of complexity too, easiest first :) (I am
> coming at this from a preservation point of view, rather than being able
> to create disk images for use with emulators, say)

Luckly I have experience with both ADSP2181 and a CPLD/FPGA. I built
my own little board to read out the internal memory from an ADSP2181,
designed signal generation board with ADSP2181, and wrote thousands of
lines of ADSP2181 code. On the other hand, I built a QBUS MSCP SCSI
with Xilinx CPLD and now working on an Altera CPLD.

I didn't read much of floppy controller but in my preliminary opinion,
CPLD/FPGA is a better fit. If you use a 2181 here, you utilize only
the (synchronous) serial port which can be easily built with a CPLD. A
CPLD on parallel port has another advantage, that you might be able to
eliminate a microcontroller which I guess is needed for a USB
sollution. I don't have knowledge of USB so please correct me if I am
wrong.

vax, 9000