A system for building complex multibit OP codes from a plurality of less complex multibit OP codes generated by a plurality of sequential keyboard entries utilizes a plurality of EXCLUSIVE OR gates which add respective bits of the OP codes generated by the sequential keyboard entries. The EXCLUSIVE OR gates each have first and second inputs and an output on which the EXCLUSIVE OR function of the input is generated. Each bit of the less complex OP codes generated by the keyboard is applied to the first input of a respective one of the EXCLUSIVE OR gates and the outputs of the EXCLUSIVE OR gates are coupled to respective parallel inputs of a storage register means. The second inputs of the EXCLUSIVE OR gates are respectively coupled to the parallel outputs of the storage register means. In operation, the bits of a first input OP code generated by the keyboard is stored in the storage means. Upon generation of a second input OP code by the keyboard the bits of the second OP code at the first inputs of the EXCLUSIVE OR gates are added to the bits of the first OP code at the second inputs of the EXCLUSIVE OR gates by the EXCLUSIVE OR gates to form a complex OP code which is then stored in the storage register means.

A control panel which provides an interface to a digital computer, and which comprises at least a data input device such as a keyboard and a data output device such as an alphanumeric display or a light emitting diode display, is tested without the use of the digital computer. The digital computer is disconnected or bypassed and the timing and other functions of the computer are simulated to enable an independent test of the data input device and the data output device which make up at least a part of the control panel.

The present invention is circuitry which is employed with a data terminal which data terminal in turn is part of a system including a main data processor. The present circuitry includes a microprocessor which is connected to the main data processor and to the keyboard. The microprocessor processes signals from both the main data processor and the keyboard. The system has a plurality of operational function circuits, such as a circuit to effect smooth scrolling on a data display means. There is logic circuitry connected between the microprocessor and the operational function circuits. The logic circuitry provides a first path which permits signals, generated in response to instructions from the main data processor, to pass therethrough to select one of the operational function circuits and simultaneously therewith to turn the selected circuit either on or off. The logic circuitry also provides a second path which permits signals, generated in response to instructions from the keyboard to pass therethrough to select one of the operational function circuits and turn circuit either on or off. A circuit to generate an impeding signal is also included and is activated by signals from the microprocessor in response to signals from the keyboard. This last mentioned generator circuit is connected to impede signals which would otherwise be transmitted along said first path, whereby said keyboard, after selecting a particular operational function circuit, can "lock in" that circuit so that the main data processor cannot turn that selected circuit off.

A programmer unit which is connected to the keyboard of a machine is capable of storing, as a program, the sequential occurance of key closures, and of supplying simulated key closures through the keyboard to the machine in the order in which such key closures were initially generated and stored. The programmer enters that key closure information into a storage register. The programmer includes a main control circuit which is responsive to various inputs supplied thereto for also entering control information into the storage register. A register control circuit is responsive to instructions from the main control circuit for entering this information into the correct position within the storage register. When the stored program is accessed, the register control circuit is responsive to instructions from the main control circuit for transmitting key closure information from the storage register in the order in which such information was originally stored. The accessed information is converted into signals which simulate key closures and such signals are connected through the matrix keyboard to the machine being controlled. A method of storing a program in such a programmer unit includes entering a pair of control words into adjacent storage locations and thereafter shifting one of the control words one storage location for each word of key closure information and filling the vacated storage locations with words of key closure information. Such key closure information may correspond to the closure of either a function key or a programmer control key. During accessing of the stored program, a third control word is initially entered and one of the pair of control words previously entered will be at a storage location which will always be adjacent the next word of key closure information which is to be accessed.

A method and a device for securely switching between operating modes of an industrial controller for machine tools or production machines are described. Before the operating mode is switched, the operator is identified by identification means that transmit to an operator's console of the controller a redundant binary enable signal after a successful identification. The operator is allowed to switch between operating modes by using the keys of the operator's console implemented in safe technology as long as the enable signal is received and is error-free. With the method and the device, the operating modes of an industrial controller for machine tools or production machines can be easily, reliably and cost-effectively switched.