An easily-upgradable computer includes a CPU board removably attached to a main board. The CPU board includes a CPU, a jump setting circuit which includes a plurality of factory-set jump switches, and a pair of first connectors electrically connected to the CPU and jump setting circuit. The main board includes a plurality of conventional peripheral devices, drivers and controllers, a clock generator, and a pair of second connectors removably coupled and electrically connected to the pair of first connectors. A wiring pattern of the CPU board electrically connects address, data, control signal, and power supply terminals of the CPU to the pair of first connectors, and a wiring pattern of the main board electrically connects the plurality of peripheral devices, drivers, and controllers, and the clock generator to the pair of second connectors. The jump switches on the CPU board are factory-set in accordance with the operational specifications of the CPU, and control the clock generator on the main board.