This is the PCB for OpenC64Cart which is a Open Hardware Cartridge for the Commodore 64. It supports 8 KB ROM images.
You will need to purchase the components separately to assemble this (eprom, reset switch, socket, etc)
For more information see the OpenC64Cart website
OpenC64Cart is designed to accept a 64 KB (512 Kilobit) (E)EPROM with a 27512-style pinout: 27512
Such chips can hold up to 8 cartridge images, which can then be selected by jumpers. Other jumpers allow the selection ROM type and of EXROM or GAME mode, achieving compatibility with many different types of ROM, from “simple” games to Ultimax cartridges.
The recommended part is Winbond W27C512.
Usage is straightforward: just insert the EEPROM in the socket making sure that the notch and all pins are aligned, set the jumpers as desired and plug the cartridge in your C64.