Hi sorry for not getting round to posting the details ages ago. I built a USB interface for the Einstein using a VDIP1 with the jumpers set J3 1-2, J2 2-3, and running in parallel FIFO mode for speed and ease of programming (you don't need to turn the Einstein's data read and writes into serial form)

http://xa.yimg.com/kq/groups/19043003/or/831124436/name/Einstein-USB-1.jpg

I didn't get round to listing the connection or explaining how it works. The VDIP1 does all the heave lifting for accessing mass storage devices connected via USB (hard drives, compact flash adapters, SD card adapters, thumb drives, etc.) it handles all of the FAT file system for you so requests to read a file from a USB thumb drive can easily be made without having to implement things on the Einstein side. Directory listings, changing directories, creating and deleting files can all be done by sending commands to the VDIP1

The problem with interfacing to the Einstein is a simple one of overcoming the lack of a chip select line on the Einstein's pipe. This is easy to resolve by ensuring that the VDIP1 only sends or receives data when the port number that it is listening to is active, using some simple glue logic to bridge the gap.

The interface is fast enough to handle all the data that the Einstein can throw at it, and will wait while the Einstein reads data at it's own pace.

It should be relatively simple to hook into the existing DOS and divert commands meant to handle files to the port that the interface is assigned to.

All the ICs shown are LN74LS00n (quad NANDs) as that is what I had laying around. The location notches are all towards the top of the picture. The IC in the top left is not used at all. The Orange wire on the right was used to ground the RS (Reset) pin on the VDIP1 when testing.

I'll trace all the connections and put together a wiring list should anyone wish to make one up themselves. However there is enough information in the picture if I don't get it done quick enough for anyone.

The VDIP1 is also capable of handling USB keyboards and Mice should anyone wish to connect those to an Einstein.

Regards,
Geoff