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MR27V6402G

4 Meg x 16 or 8 Meg x 8 Production Programmed Read Only Memory (P2ROM)

4,194,304-word × 16-bit/8,388,608-word × 8-bit electrically switchable configuration
+3.0 V to 3.6 V power supply
Access time 80 ns MAX
Operating current 30 mA MAX
Standby current 10 µA MAX
Input/Output TTL compatible
Three-state output
Media:mr27v6402g.pdf

Oki Semiconductor's Cross Reference lists two perfect matches: