Jeff> The 8500 and the Umax S900 have exactly the same firmware.    They 
Jeff> both use the ROM Revision $77D.28F2.  In fact, the 7500, 8500, 9500, 

Jeff> The four ROM chips are marked 341S0168 through 341S0171 for 
Jeff> $77D.28F2.   They are marked 341S0106 through 341S0109 for $77D.28F1.

Yeah, incredably detailed information..
I have checked inside and surely U13-U16 are marked as 341S0168-171 
with SEC manufacturing.
---
Makoto Fujiwara, 
Chiba, Japan, Narita Airport and Disneyland prefecture.