In an exemplary data entry terminal, the keyboard, display module, and terminal processor board form respective subassemblies which can readily be disconnected from each other electrically and slidably removed from respective channels of a U-shaped housing extrusion. A cathode ray tube of the display module may be viewed through a window forming part of the keyboard subassembly. In the case of a pizza home delivery system, bar codes identifying the orders are printed out for facilitating handlin...

A demultiplexer circuit which extracts from an incoming time division multiplexed digital bit stream any combination of PCM encoded words (in separate channels), or data bits irrespective of the rate of the latter or the position of the data bits in a given channel. The demultiplexer circuit includes a random access memory (12) (RAM) for storing information as to the channel(s) to be demultiplexed out of the incoming digital bit stream. A counter (13) operates in synchronism with the received bi...

A display illuminating circuit for a repertory dialer telephone set allows for a subscriber to operate a desired repertory button in low ambient light emergency situations. The circuit illuminates the desired buttons by distinguishable colors of light-emitting elements. Activation of the illumination circuit occurs in response to the telephone set going off-hook and then only for a limited period to conserve battery life. A battery voltage monitoring arrangement provides an indication when a loc...

A switch circuit arrangement, wherein a plurality of switch means each comprising paired display lamp and self-restore type switch contact are provided, and a control circuit is also provided in association with said switch means. By actuating any one of the switches, a display lamp paired therewith is lit, and at the same time, a control signal is derived from a detector circuit including I.sup.2 L element. The control signal thus derived is passed to a controlled device, whereby the display la...

In a time-division multiplexing system, data are supplied to the multiplexer with different speeds. Depending on the speed, time slot groups are allocated to the data, with the number of allocated time slots increasing with the speed. The search for groups of free time slots occurs in a fixed sequence. Data to which time slot groups at the end of the fixed sequence have been allocated, are relocated to time slot groups which have become free nearer the beginning of the sequence. The allocated ti...

A subscriber data distribution system comprising first means for translating data received from a transmission line and transmitting the data to a subscriber terminal via a subscriber drop, second means for translating data received from a subscriber terminal and transmitting the data to the transmission line, the first and second means including means for isolating the transmission line from the subscriber terminal, and for regenerating the data transmitted both to and from the subscriber termi...

A circuit for supplying drop current to the subscriber connected to the remote terminal of a central office powered telecommunications system. A switching regulator is included in the circuit for generating the drop current. The switching regulator adjusts its conduction time as a function of the length of the loop connecting the subscriber to the terminal such that the subscriber consumes only that power required by the loop length. The switching regulator operates in response to a reference cu...

In a time division multiplex system having chronological grouping of optically transmittable PPM signals, the PPM signals of one half of the time channels are transmitted as pulses in one half of each pulse frame and the PPM signals of the other half of the time channels are transmitted as pulse pauses in the other half of each frame for the purpose of the co-transmission of a clock frequency component without providing a separate synchro time slot. For this purpose, PPM pulses are formed and tr...

An arrangement for traffic analyzing for public telephone stations which are served from a telephone exchange. The exchange transmits charging pulses to the telephone stations through telephone subscriber's lines, when calls are requested from the telephone stations. A charging pulse counter is accessed through a charging pulse detector when a call is made. The counter counts the number of detected charging pulses during the observation period allocated to the calling telephone station. An analy...

A video display terminal permitting substantially continuous scrolling of the display. Each character row of the display is stored in the display memory in a memory segment which also stores one or more parameter bytes associated with the character row. A first parameter byte portion indicates the number of the scan line on which the display of that character row is to commence during the current frame. A second parameter byte portion indicates the number of scan lines of that character row whic...