| 摘要 |
PURPOSE:To surely protect secrecy for a program by constituting a microinstruction decoder circuit by a programmable logic arrays programmed electrically externally. CONSTITUTION:The microinstruction decoder IDEC decoding a microinstruction read from a control storage CM storing a microinstruction is constituted by a programmable logic array rewritable electrically externally. Since the logic of the microinstruction decoder circuit IDEC is set freely and individually for each user, the correspondence between the output of the microinstruction decoder circuit IDEC and the program are made individual by the logic of the microinstruction decoder circuit IDEC. Thus, the sure secrecy protection of the program is attained. |
