Abstract: An allocation controller providing for equal priority sharing of multiple resources by a plurality of central processing units. Conflicts resulting from simultaneous requests from several CPUs for access to one of the common resources are resolved at a high rate of speed. In addition, an approximately statistically equal probability is maintained for access of the common resource by all the central processing units.

Abstract: A line circuit which allows a multiple line telephone to operate like a private branch exchange (PBX) telephone. Solid state hold and flashing circuits drive a light emitting diode in each telephone connected to the same line.

Abstract: A protecting arrangement is dislcosed for multiple loads supplied from a single DC power source. Each load is monitored by a separate protection circuit. Detection of an over-current condition associated with one of the loads will cause the associated protection circuit to assume a non-conducting state and provide a visual indication of same. Periodically enabled common reset means are provided to restore conduction to non-conducting protection circuits following removal of the cause of over-current.

Abstract: An allocation controller providing for equal priority sharing of duplicate copy multiple resources by a duplex plurality of central processing units. Conflicts resulting from simultaneous requests from several CPUs for access to one of the common resources are resolved at a high rate of speed. In addition, an approximately statistically equal probability is maintained for access of the common resource by all the central processing units.

Abstract: An improved selector card assembly for use in a paystation coin handling mechanism wherein the polarizing magnet normally molded into the end of the card is mounted onto the card by a pair of tines and a central saddle like tongue portion. Thus leaving the polarizing magnets poles exposed and closer to the coin magnet core extensions.

Abstract: A tool for extracting a printed circuit card from a holder the latter having a top and bottom guide tracks and a rear wall having contacts engageable by terminal tabs on the card, comprising a pistol grip type handle and a shaft extending perpendicularly outward from the handle. The shaft includes a hook on one end and is mounted to the handle at an opposite end. A plunger including a stop bracket is slideably mounted on the shaft and is propelled forward via a spring loaded trigger bracket. The hook is applied to the rear of the circuit card handle and the stop bracket rested on the bottom guide track. When the trigger is squeezed the hook pulls and extracts the circuit card from the holder.

Abstract: Signals from line circuits requesting service are transferred to a T1 channel via a Pulse Amplitude Modulated (PAM) bus. The number of line circuits which can be served by a T1 line is not limited by the capacity of the T1 line since the probability of all line circuits requesting service at the same time is extremely low. A processing unit detects requests for service and assigns them a slot in a memory which defines the scanning sequence for insertion of line circuit signals in the T1 channel.

Abstract: A circuit for simulating the effects of a temperature change in a digital transmission medium. The circuit generates lengthened or shortened frequency pulses digitally by operating a pulse counter to reset early for a shortened pulse or skip a timing pulse for a lengthened interval pulse. A second counter and associated decoder are utilized to alternately control the operating modes.

Abstract: A microcomputer controlled key telephone line circuit for use in a key telephone. A microcomputer is used to sequentially and alternately scan the ringing leads and tip and ring leads associated with connected line circuits and A leads associated with connected telephone stations. The microcomputer operates in response to changes in the status of these leads to control the normal key telephone functions such as line pickup, hold and ringing current detection, lamp illumination and tone signaling.

Abstract: A monitor circuit, for use in a switching system which detects pulse failures through use of a pair of timing counters. A flip-flop enables and clears each counter alternately in response to detection of the monitored pulse.

Abstract: A tool for inserting a printed circuit card into a holder the latter having top and bottom guide tracks and a rear wall having contacts engageable by terminal tabs on the card, as well as the extraction of such cards frm the holder, comprising a pistol grip type handle and a shaft extending perpendicularly outward from the handle. The shaft includes a hook on one end and is rotatably mounted to the handle on an opposite end. A plunger including a retractable stop bracket is slideably mounted on the shaft and is propelled forward via a spring loaded trigger bracket. By rotating the shaft and retracting the stop bracket the hook is engaged to the bottom guide track allowing the plunger to insert the circuit card into the holder and its associated contacts, when the trigger is squeezed. To extract the card the shaft is rotated to engage the rear of the circuit card handle and the stop bracket rested on the bottom guide track.

Abstract: A tool for inserting a printed circuit card into a holder the latter having top and bottom tracks and a rear wall having contacts engageable by terminal tabs on the card, comprising a pistol grip type handle and a shaft extending perpendicularly outward from the handle. The shaft includes a hook on one end with an opposite end mounted to the handle. A plunger is slideably mounted on the shaft and is propelled forward via a spring loaded trigger bracket. With the hook engaged to the bottom guide track the plunger is used to push and insert the card into the holder when the trigger bracket is squeezed.

Abstract: An arbitration controller providing for equal priority sharing of a resource by a plurality of central processing units. Conflicts resulting from simultaneous requests from several CPUs for access to the common resource are resolved at a high rate of speed. In addition, an approximately statistically equal probability is maintained for access of the common resource by all the central processing units.

Abstract: This circuit provides a minimally sized bidirectional asynchronous automatic interface between a high speed data processing system and one of a plurality of data terminal devices.

Abstract: An arbitration controller providing for equal priority sharing of duplicate copy resources by a duplex plurality of central processing units. Conflicts resulting from simultaneous requests from several CPUs for access to the common resource are resolved at a high rate of speed. In addition, an approximately statistically equal probability is maintained for access of the common resource by all the central processing units.

Abstract: A monitor circuit, for use in a switching system which detects pulse failures through use of a pair of timing counters. A flip-flop enables and clears such counter alternately in response to detection of the monitored pulse.

Abstract: An arbitration controller providing for equal priority sharing of a resource by a plurality of central processing units. Conflicts resulting from simultaneous requests from several CPU's for access to the common resource are resolved at a high rate of speed. In addition, an approximately statistically equal probability is maintained for access of the common resource by all the central processing units.

Abstract: A circuit which monitors the frequency of an incoming signal and synchronizes an internally generated clock signal to the incoming signal. A retriggerable monostable multivibrator monitors the incoming signal which is synchronized by means of a phase lock loop circuit to a signal generated by a voltage controlled multivibrator. A crystal oscillator provides clock signals upon detection of failure of the incoming clock signal.