A system includes a cartridge attachment section and a cartridge attachable to the cartridge attachment section. The cartridge includes a board supporting portion supporting a board provided with an electrical interface. The cartridge attachment section includes a slider having a first wall, a second wall and an electrical contact. During insertion of the cartridge, the slider is moved from a second posture where the electrical contact separates from the electrical interface into a first posture where the electrical contact contacts the electrical interface. Upon completion of attachment of the cartridge, the first wall and the second wall are received respectively in a first space and a second space defined between the cartridge and the cartridge attachment section.