Abstract: A method and circuitry are disclosed for asynchronously transmitting binary data over a communication pair without the use of start or stop bits. During a non-data transmitting state a quiescent differential voltage, which is intermediate to the binary data differential voltage levels, is placed on the pair. The start of a data transmission is signaled by a transition of the differential voltage from the quiescent state voltage to the binary voltage of the first data bit of the data transmission. Since all data transmissions are of known bit lengths, the end of a data transmission is determined by counting data bits.

Abstract: In a planar ac plasma panel, display cells are formed by the intersection of row and column conductors which are embedded at lower and upper levels, respectively, in a single dielectric layer which adjoins an ionizable display gas. A glow suppression pad, embedded at the upper level, is located adjacent each display cell. The glow suppression pad is capacitively biased from the row and column electrodes at a voltage which prevents unwanted ionization of the display gas between adjacent display cells.

Abstract: An interconnection matrix is disclosed for connecting inputs and outputs of logic circuit of a programmable logic array (PLA). The interconnection matrix consists of row conductors each connected to an input of a logic circuit and segments of column conductors each connected to an output of a logic circuit. By limiting the interconnection capability of each column conductor several column conductors each electrically isolated from each other can share the same column of the interconnection matrix. The resulting PLA can perform various logic functions using an interconnection matrix which does not grow geometrically with an increase in the number of logic circuits.

Abstract: The disclosed real time dictation arrangement time-shares several transcribers among various users requiring dictation service. The dictation from a user is partitioned into time sequential dictation segments. A controller unit distributes the segments of dictation from each of several users to several transcribers. Voice storage is provided so that users do not have to wait to speak and so that transcribers can pause or repeat the speech being worked on. The controller unit collects the transcribed dictation from the transcribers, and delivers the text to the proper user. A video terminal enables each user to see the transcribed dictation almost as fast as it is spoken, and enables the user to control by means of a cursor where transcribed text is to be inserted.

Abstract: The disclosed communication system operating mode signaling method and arrangement utilizes dc current signaling over the loop facility connecting a customer to a central office (CO). The dc current on the facility provides concurrent on-hook/off-hook signaling and voice/digital data operating mode signaling between the customer and CO. A current flow in a first direction over the facility signals a voice operating mode while a current flow in a second direction signals a digital data operating mode. A customer signals a change in the operating mode by reversing the direction of allowed current flow at the customer unit. The resulting interruption of the current flow is detected at the CO which responds by reversing the direction of current flow over the facility. The reappearance of current flow over the facility distinguishes a customer's change in operating mode from an on-hook condition.

Abstract: A method and arrangement is disclosed for providing a digital conference capability for subscribers of a time division multiplex (TDM) communication system. Each conferee's pulse code modulation (PCM) signal is assigned one of N conference time slots of the TDM system. The arrangement serially stores in memory the PCM signals of N-1 time slots. Circuitry serially generates the sum of the previously stored N-1 time slot PCM signals concurrently with the serial writing into memory of the PCM signal of each time slot. During each time slot a composite PCM conference signal is formed by combining the PCM signal of that time slot with the summed PCM signal and distributed to the conferees assigned to that time slot.

Abstract: A method and apparatus for the transmission of two-tone pictures progressively in several stages. Progressive transmission enables a viewer to receive and utilize pictures in a small fraction of the normal transmission time. In a first stage, information representing groups of picture elements of preselected lines of the scanned picture is transmitted which allows a coarse version of the picture to be reproduced at a receiver. During the subsequent stages the horizontal resolution of the previously transmitted scan lines is improved and additional scan lines are transmitted in a specific order until the received picture is an identical copy of the original picture. The progressive picture information is efficiently transmitted in one of several line-by-line codes resulting in a total transmission time not significantly longer than the time for a nonprogressive transmission.

Abstract: A data communication arrangement is disclosed for multiplexing an asynchronous binary data signal with a synchronous binary data signal by the timely insertion of an extra data bit in selected synchronous data words and by delaying the transmission of the resulting multiplexed data words. The extra data bit is generated when a binary level transition occurs in the asynchronous binary data signal. The transmission of the multiplexed data word is delayed a fixed amount of time relative to the binary level transition of the asynchronous signal to preserve the timing between transitions in the asynchronous signal. The received multiplexed data words are demultiplexed into a synchronous and asynchronous binary data signals. The demultiplexed asynchronous binary data signal emerges having transition timing which is the same as the transition timing of the original asynchronous binary data signal.

Abstract: A frame synchronization arrangement is disclosed for use in a digital data transmission system which utilizes a redundant data word transmission. A selected data word of each frame of data having a fixed location relative to the frame boundary is transmitted twice to provide a framing signal for the receiver circuit. At the receiver circuit the data is shifted through a shift register where a comparator checks predetermined locations of the shift register for redundant data words in the received data stream. Once the redundant data words are detected a valid word received signal is generated. The existence of the valid word received signal together with the known relationship between the location of the redundant word and the frame boundary is used to provide a framing signal.

Abstract: A line circuit is disclosed for controlling communications over a communication pair between a switching machine and a key telephone station. The line circuit includes a dual sensitivity shunt detector arrangement (103, 104, 105) for improved detection of dc transients and ac ringing voltage signals appearing across the pair. A current diverter circuit (104) switches the sensitivity of the shunt detector arrangement depending on the operating state of the key telephone station.

Abstract: There is disclosed a line circuit for establishing a hold condition on a communication line, extending between a switching machine and a key telephone station, during an open switching interval (OSI) when no current flows on the communication line. The control signal required to enable the hold circuit is arranged to be time dependent. For a fixed time interval, which bridges the OSI period, after the telephone station answers a ringing line a hold condition is enabled (402) exclusively by a control signal on the A lead from the station. This time dependent hold enable arrangement permits a hold capability during an OSI condition. After this time interval elapses (403) a hold condition is enabled by (404) a joint signal condition on the A lead and a current continuity condition on the communication line.

Abstract: A computer input/output arrangement is disclosed which utilizes a rotate memory instruction of a computer instruction set for performing a bit by bit read/write data transfer between the computer memory and a connected peripheral device. The arrangement enables the rotate memory instruction to perform read and write steps simultaneously from memory and the peripheral device. During the read step data is simultaneously read from the memory location and the peripheral device into associated locations in a computer register. The register data is rotated such that the received data in the peripheral device bit location is rotated into the memory bit locations of the register while simultaneously rotating a memory data bit into the peripheral device bit location. The write step writes register data from the peripheral device bit location to the peripheral device while simultaneously writing the data from the memory bit locations into the memory.

Abstract: The disclosed one piece self-locking switch contact member is arranged to mount on the handle of a printed circuit board. The switch member functions as a movable switch contact which is operable from the user's finger pressure to electrically connect together two test terminals located in an aperture of the handle. The switch member is made of a resilient dielectric material having an open loop end arranged for a snap-on lock mounting between the aperture and an edge of the handle. The other end of the switch member contains an electrical contact area and is cantilevered by the mounting to provide a resilient movement which permits contact with the test terminals when acted upon by finger pressure.

Abstract: A communication arrangement is disclosed which enables data calls between data terminals and a computer over a telephone network without significantly increasing the call blocking probability of the telephone network. When a data call, consisting of several data transactions is originated, the arrangement stores the called station information for later use in reestablishing a network connection on subsequent data calls between the same users. By disassociating the data terminal-computer data call signaling from the telephone network data call signaling, the telephone network is available for other data or voice traffic during the time when no data calls are active. A termination signal cancels the stored information and concludes the data call between the users.

Abstract: A call screening arrangement is disclosed for an intercom communication system in which call features are activated by entering a two digit code from the rotary or multifrequency dial of the connected station sets. Incoming calls to a called station are screened according to the type of call features activated at the called station. The particular call screening feature activated is determined by the order of the sequential activation of the existing Call Forwarding, Callback or Do-Not-Disturb call features. The call screening features enable incoming calls controlled by either a Call Forwarding or Callback feature to selectively bypass a Do-Not-Disturb call blocking feature at the called station. When activated individually the Call Forwarding, Callback and Do-Not-Disturb features perform their individual call control routines.

Abstract: An infrared personnel locator system using a periodic unique infrared identification code emitted from a battery-powered transmitter unit to identify the person carrying the transmitter unit to an overhead infrared receiver as the person enters the receiver's monitoring zone. The transmitter unit identification code together with the receiver identification code is communicated to a common control unit which displays the location of all of the transmitter units. For paging, the system provides alerting units which are selectively operated in the zone closest to the person being paged. Additionally, the system controls electronic locks for restricting access of users to certain locations or equipment. A telephone interface provides system access from the telephone network.

Abstract: The disclosed full duplex bit synchronous data rate buffer (15) adapts high speed burst data signals for transmission over low speed data facilities. The data rate buffer (15) includes a buffer control circuit (201-205, 105) for interactively controlling a first data buffer (101) for down-converting the high speed signals (107) to low speed signals (109) and a second data buffer (102) for up-converting low speed data signals (108) to high speed burst data signals (106). The data rate buffer (15) accepts random changes in the length of each high speed burst data signal without a loss in bit synchronism and adjusts for changes in the number of burst data signals contained in each frame.

Abstract: A telephone signaling interface (I1) enables compatible communications between a modified telephone station set (S1) and a key telephone system (KTS1). Separate alternating voltage control signals from the key telephone system (KTS1) are amplitude and polarity modulated and combined by the interface (I1) to provide ringing, switchhook supervision and visual signaling to station set (S1) over a single signaling wire pair (C1). Current flow on the signaling pair (C1) in one direction provides visual signaling while distinguishable amounts of current flow in the opposite direction provide the supervision and ringing signals. Interruption of the supervision current is converted by interface (I1) into an A lead supervision signal for the key telephone system (KTS1). Voice communication between the modified station set (S1) and the key telephone system (KTS1) occurs over a separate voice communication pair (V1).

Abstract: A two-terminal tone generating hold impedance is disclosed which is powered from a central office telephone line and provides the functions of a hold impedance in a key telephone line circuit while providing an audio tone signal to an associated telephone line when the line is placed in a hold condition. The tone generating hold impedance consists of an oscillator circuit which is self-exciting upon the application of a dc voltage resulting from the connection of the tone generating hold impedance to the telephone line. In another embodiment a line powered music receiver functions as a hold impedance and applies music, received via radio or cable transmission, to the line placed in a hold condition.

Abstract: A telephone station set (S1) is arranged to communicate voice signals over a voice communication pair (V1) and to communicate ringing, switchhook supervision and visual signaling over a separate signaling pair (C1). An amplitude and polarity modulated alternating voltage on the signaling pair (C1) provides current flow in one direction for visual signaling while distinguishable amounts of current flow in the opposite direction to provide switchhook and ringing supervision. The switchhook supervision current and the ringing signal current both flow through a series connection of a buzzer (B1) and a break switchhook contact (SH2) in the telephone station set. An off-hook condition at the telephone interrupts current flow on the signaling pair (C1) providing a switchhook supervision signal while simultaneously terminating the ringing signal.