Deaton,

Please refer to my post dated 1-8-2001 02:26 PM on Yamaha PSR9000 SIMMs for more information and strategy to get the right SIMMs that work. Yamaha PSR9000 and 9000Pro use the same SIMMs.
http://www.synthzone.com/ubbs/Forum37/HTML/001094.html

Good luck in SIMM hunting,

Paul Ip
from Texas