1. A system LSI that integrates, on a single semiconductor, a logic circuit, a CPU (Central Processing Unit), and a program memory storing a program of the CPU, the system LSI comprising: a program eraser that is executable to erase contents stored in the program memory, the program eraser having an inputter to control execution of the erasure of the contents; at least two program erasing trigger terminals, one of the program erasing trigger terminals being connected to the inputter of the program eraser; and a short bar to short-circuit the program erasing trigger terminals, wherein the short-circuit of the program erasing trigger terminals by the short bar disables operation of the program eraser at a manufacturing stage of the system LSI; wherein when the program erasing trigger terminals are not short-circuited and current is applied to the system LSI, a voltage at the inputter of the program eraser causes the program eraser execute a program erasing operation to erase the contents stored in the program memory; wherein the short bar is formed of a material having a melting point such that the short bar is thermally cut by reflow, when the system LSI is mounted to a printed circuit board, thereby ending the short-circuit of the program erasing terminals provided by the short bar; wherein by providing a pattern on the printed circuit board to short-circuit the program erasing trigger terminals, the short-circuit of the program erasing trigger terminals by the pattern disables operation of the program eraser while the system LSI remains mounted to the printed circuit board; and wherein the system LSI is configured such that upon detaching of the system LSI from the printed circuit board, the program erasing trigger terminals are no longer short-circuited, and when current is applied to the system LSI, the voltage at the inputter of the program eraser causes the program eraser to execute the program erasing operation to erase the contents stored in the program memory.