ROM BIOS of The Plus Hardcard 50 II XL

Two EPROM chips 
The original chips are TI TMS27PC256-20NL

One located in socket U201 - HC50U201.BIN  (Mine has N13 stamped on chip)

One located in socket U218 - HC50U218.BIN   (Mine has R14 stamped on chip)

Image source: TOP853 Programmer