Apple2 USB Stick interface with Vinculum chip

["RedskullDC" <RDC@oz.org>]

Hi All,

The Vinculum USB DIP parts arrived yesterday, and work has begun
on a prototype board.
With any luck, I should have the protoype ready by the weekend
to start writing the firmware.

You can see pics at:

http://au.geocities.com/redskulldc/a2usb.jpg   (big 520K)
or
http://au.geocities.com/redskulldc/a2usb_sm.jpg  (small 154K)

Wiring is about half finished underneath.

The VDIP part is at the top right.

The circuit will be fairly simple:
74LS245 to buffer the data lines,
a few bypass caps,
a small eprom/flash chip to hold the firmware.
(I'm using an NVRAM during development since it makes it much easier to
do firmware updates)
and an Altera CPLD (EPM7032 5V, only because I had a few in the junk box)
which will do the $C800-$CFFF flip-flop logic, plus a few other things.

There will be a JTAG port on the board to allow reprogramming of
the CPLD.

It will basically allow any Apple2 with expansion slots to read/write to a 
USB-stick.
Haven't decided whether to bypass the VDIP's FAT file system support, and 
use
raw block read/writes, so that the stick would be in native prodos format,
or whether to stick with the FAT filesystem in the VDIP firmaware, and have
"virtual" 32MB prodos volumes online.
Depends on the VDIP firmeware to some degree.

Any comments/suggestions?

Cheers,
Red