Abstract: An instruction decoding unit in a microcomputer is disclosed having an instruction word capable of being selected by a user to conveniently produce application software while maintaining security. The decoding unit in a microcomputer includes an instruction register for storing instructions fetched from a memory, an instruction decoder for decoding instruction codes of the instructions stored in the instruction register and for designating micro-instructions to be executed, a micro-ROM for outputting a series of the micro-instructions designated by the instruction decoder, and a user instruction selector for selecting or changing the micro-instructions of the micro-ROM in response to user's selection so as to change the operation of an instruction word.

Abstract: An instruction decoding unit in a microcomputer is disclosed having an instruction word capable of being selected by a user to conveniently produce application software while maintaining security. The decoding unit in a microcomputer includes an instruction register for storing instructions fetched from a memory, an instruction decoder for decoding instruction codes of the instructions stored in the instruction register and for designating micro-instructions to be executed, a micro-ROM for outputting a series of the micro-instructions designated by the instruction decoder, and a user instruction selector for selecting or changing the micro-instructions of the micro-ROM in response to user's selection so as to change the operation of an instruction word.

Abstract: A communication system and method requiring only a single line for communication among integrated circuits (ICs). The system includes: a single communication line; plural ICs coupled to the single communication line; one of the ICs operating as a master IC; one of the ICs operating as a transmitting IC and one of the ICs operating as a receiving IC according to a designation by the master IC. The master IC transmits, on the single communication line, a reference signal having a reference signal width, C.sub.PW, to the other ICs. The master IC designates a first one of the ICs and a second one of the ICs as a chosen transmitting IC and a chosen receiving IC, respectively, for an imminent data-transmission operation, by transmitting signals of differing widths (relative to the reference signal width) over the single communication line.

Abstract: An improved address re-designate circuit for a programmable microcontroller which is capable of arbitrarily selecting a peripheral circuit and re-designating an address corresponding to the selected peripheral circuit has the advantage of easily being programmed since the user can arbitrarily select a peripheral circuit disposed in the microcontroller chip according to a desired function and can re-designate an address thereof.

Abstract: An improved automatic data backup apparatus for a microcomputer capable of automatically backing up a user's program at a central processing unit(CPU), which includes a central processing unit(CPU) for performing a user program and a monitor program outputted from a first emulator input/output circuit and a data/address bus; a second emulator input/output circuit for outputting a register signal applied thereto and for inputting/outputting a data between a register data bus connected to an emulator and a backup register bus; and a data backup storing circuit for automatically backing up a data stored in a register of the CPU corresponding to a user program performed in the CPU in accordance with a monitor program request signal outputted from the second emulator input/output circuit, a register signal, a register recording signal, and a register judgement signal and for applying a data stored in a register in the CPU corresponding to a user program which is changed by a backed-up monitor program.

Abstract: A pulse width modulation (PWM) circuit is disclosed for multiple channels. The circuit allows output pulses of a PWM signal for each channel to be distributed not simultaneously but with a time difference so that the power consumption is temporally distributed.