Yamaha SY99 ROM-Upgrade to OS Version 1.57 :

Required Chips

+++ BOARD DM1 +++

IC 101 (1 Mbit EPROM DM1) SEQ-ROM v1.2 Sequence MEMORY ROM D  (XK167A00) #	= M5M27C201K (XJ616C00) Eprom

IC 111 (4 Mbit EPROM DM1) ROM1 	 v1.57 Program TC574000D-120 (XJ613H00) #	= TC574000D  (XJ613D00) Eprom

IC 112 (1 Mbit EPROM DM1) ROM2 	 v1.2 Voice   XK165A00 	 (pka XJ614C00) #	= HN27C101AG (XJ614B00) Eprom

IC 113 (1 Mbit EPROM DM1) ROM3 	 v1.2 Library XK166A00	 (pka XJ615C00) #	= HN27C101AG (XJ615C00) Eprom

IC 128 (OTP DMI) CPU H8/532 		 v1.5 HD6475328CP10   		 (XI722G00) #


You'll need: 

3 x 27C101 xxxx or similar (IC 101, IC 112, IC113)

1 x 27C4001xxxx or similar (IC 111)