PDF of 329 KB named 25C040, indexed as a schematic although the name points to a 25-series SPI serial EEPROM, where 040 conventionally denotes 4 Kbit capacity.

Here is a 323 KB PDF named for the 25AA040, 25LC040 and 25C040, a Microchip family of 4 Kbit SPI serial EEPROMs; despite the schematic label it is a datasheet.