[Robotgroup] USB Interface chips?

[Clendon Gibson]

A friend of mine has an old instrument that he would like to add an USB interface to. The instrument has an 8051 micocontroller and related circuitry. 

What I would like to do is either find a USB interface chip that speaks microcontroller on one side and USB on the other, or find an USB Microcontroller that uses the 8051 instruction set. (Don't want to have to re-write all that code since it works and is pretty much bug free.)

Any suggestions?

Thanks!