Nanocomputer refers to a computer smaller than the microcomputer, which is smaller than the minicomputer.
Microelectronic components that are at the core of all modern electronic devices employ semiconductor transistors. The term nanocomputer is increasingly used to refer to general computing devices of size comparable to a credit card. Modern single-board computer such as the Raspberry Pi and Gumstix would fall under this classification. Arguably, smartphones and tablets would also be classified as nanocomputers.