This Cartridge PCB uses one programmable read-only memory (PROM) from NEC named D23128C.

This is a digital memory where the setting of each bit is locked by a fuse or antifuse.

Such PROMs are used to store programs permanently. They are frequently seen in video game consoles, or such products as electronic dictionaries. For example this PROM was also find in Sinclair ZX Spectrum mainboard.