This Cartridge PCB uses one ROM from TOSHIBA named TMM23256P. This chip is a Mask Read Only Memory with a low bit cost most suitable for use in character generator.

Its built in memory matrix has 32,768 x 8bit word, which means 32 Kbytes of data available. It has two separate row and column decoders which are interfaced to the memory cell array.

There are two separate buffers for input and outpout data driven by a controller with a clock signal.

There is an Hex Inverter CMOS chip by TOSHIBA also but, looking at the pcb circuit seems to be powered but not to used.