Abstract: Each vehicle of a transportation system is provided with a radio transmitter providing electable and different sequences of signals, one part of the signal identifying the vehicle, and another changing sequence of signals, either under operator control or automatically by attachment to the odometer, to indicate the present position of the vehicle on a scheduled route. The home of a passenger desirous of meeting a particular vehicle at a particular pickup point is provided with a radio receiver with selectable detectors which can be set to detect the signals from a particular vehicle transmitter, and provide a visual or audible indication of the present position of the vehicle on the scheduled route. Pre-specified settings of the receiver, and corresponding detectable signals, inform a passenger of no service or delayed service.

Abstract: In a data processing system which predecodes and queues a plurality of instructions for sequential presentation to an execution unit, and which includes a plurality of instruction-addressable general registers which can be utilized for temporary data storage or source of address modifying information, an interlock mechanism is provided to detect when an instruction is being decoded which requires use of a general register for address modification, but which register has not yet received new data by execution of an instruction awaiting execution in the queue of instructions. Two fields are associated with each instruction awaiting execution in the instruction queue. They identify one or more of the general registers to be loaded with data by execution of the instruction.

Abstract: A high speed multiply apparatus minimizes latch requirements and I/O pin requirement between chips by a new configuration which iteratively adds four multiples of a multiplicand in a stage of 4-2 carry save adders which then feed four-bit parallel adders each having four sum outputs and a carry output from the highest order bit position. Only the sum outputs are latched and then fed to a carry propagate adder on each iteration for addition to the previous partial products. Only the single carry output from each of the 4-bit parallel adders needs to be latched and then fed to another 4-bit parallel adder.

Abstract: In a high-performance computer which prefetches and predecodes instructions for sequential presentation to an execution unit, at least three separately gated and sequenced multi-instruction buffers for prefetched instructions permit continued sequential predecoding and buffering of instructions from three independent instruction streams identified by multiple branch instructions, some of which may be conditionally executed. A number of stored pointers identify particular ones of the multiple instruction buffers. Various branch instructions are predicted to be successful or unsuccessful. Result signals from the instruction execution unit, in response to execution of conditional branch instructions, will control the setting of various pointers and busy triggers associated with each instruction buffer, causing the next sequential instruction transferred to the instruction execution unit to be from the proper instruction stream based on the result of the branch on condition instruction.

Abstract: In a data processing system which includes a base central processing unit, channel, and input/output (I/O) interface to which peripheral devices may be attached, a special attachment is disclosed. The attachment made to the base I/O interface includes connector circuitry which is required when the signals on the input/output interface must be repowered to peripheral devices in an expansion input/output unit, power isolation must be provided between a base data processing system and I/O expansion unit, or a remote peripheral device is to be attached to the base data processing system I/O interface. The connector circuit includes logic which responds to the normal I/O interface signals to energize drivers in the connector circuit to achieve repowering of signals on bidirectional signal lines and unidirectional signal lines.

Abstract: Disclosed is a decoder which receives a number of coded binary-weighted input signals and which provides, on a plurality of output signal lines, a threshold related to the coded value of the input signals. The threshold is defined at the output as a consecutive sequence of output signal lines having a binary 0 value on one side of the threshold, and a consecutive sequence of output signals on the other side of the threshold having a binary value of 1. In one embodiment, a single level of binary logic receives n input signals and produces a threshold on m = 2.sup.n -1 output signal lines. A second embodiment receives n input signals which are divided into groups of signals, each group of which is applied to an intermediate threshold generator, the outputs of which are combined in a final level to provide m output signals.

Abstract: A data processing system with improved input/output (I/O) techniques is disclosed. The input/output control logic, or channel, of a central processing unit is connected to a plurality of peripheral input/output device control units, in parallel, by a plural line interface bus which includes bidirectional data transfer lines and bidirectional address transfer wires. The interface bus also includes unidirectional lines to and from peripheral device control units which synchronize operation of use of the bus. Several forms of I/O communications are shown to be controlled by the interface bus and include, direct processor controlled data transfer with simultaneous transmission of data and commands to peripheral devices, cycle steal data transfers permitting concurrent input/output operations and central processor program instruction execution, and peripheral device initiated interrupt requests to the central processor.

Abstract: Signals generated by double frequency magnetic recording are received by logic which is controlled, and sensed, by a sequence of program instructions from a microprocessor. In particular, a special pattern of signals is to be recognized. The special pattern of signals is known in the magnetic disc recording art as an address mark which is a unique pattern of interspersed clock signals and data signals. The pattern is made more unique from any other pattern of data by the fact that certain of the clock signals are missing. The ability to utilize a microprocessor, which is relatively slow, in a magnetic recording system in which the bit rate is relatively fast, is enhanced by a particular processor program instruction which is effective to access a next following instruction from program storage and then stop the clock of the processor. The clock is re-started, and therefore execution of the next instruction initiated, upon receipt of a timing signal from the logic receiving the signals to be detected.

Abstract: The interface between I/O control logic, or channel, and peripheral devices permits simultaneous transfer of command, device address, and data, and includes logic in a peripheral device control unit for dynamic change of the attached peripheral device interrupt priority level while the device may be executing a prior command. The I/O control logic includes means for initiating serial poll signalling while other transfers are taking place on the interface.

Abstract: Common logic in a peripheral device control unit responds to a serially propagated poll signal from I/O control logic, or channel, along with a coded signal identifying either a poll for a cycle steal request or a poll for an interrupt request having one of several priorities. The poll signal received will be captured or propagated to following control units dependent upon whether the control unit has requested a cycle steal transfer, or has requested an interrupt at the priority level indicated by the coded signal accompanying the poll signal. Proper functioning of poll capture or propagation is possible even though one of the control units is physically removed from the serial chain of control units.

Abstract: Logic circuits in an adder for use in data processing for the detection of a sum of all ZEROES together with the mathematics upon which the circuits are based. Circuits and mathematics are also disclosed for a detection of a sum of all digits equal to the radix less one. Each of these detected sum conditions are produced prior to or at least concurrently with the production of the sum itself.

Abstract: Error detection for an associative directory or translator, composed of registers, comparators, and encoder which provides a binary code representation of the location of the register at which a compare occurred, includes a random access register array which responds to the coded location information to read out binary data to be compared with the binary data utilized in the associative compare of the directory or translator.

Abstract: Binary logic is added to the binary logic normally utilized for the purpose of generating and decoding binary code combinations which reflect the order of use of a number of units, utilized in sequence, to thereby indicate the unit least recently used (LRU). Disclosed is the utilization of six binary bits which are updated in accordance with a sequence of use of four units to thereby indicate the least recently used one of the four units. In accordance with known LRU techniques, there are 24 valid binary bit combinations that reflect the sequence of use of the four units. The provision of 6 binary bits in the LRU code are capable of assuming 64 different permutations, therefore 40 combinations of binary bits are considered invalid when utilizing the LRU code.

Abstract: A parallel adder with sequential carry ripple is subdivided into sections. Detector circuits are distributed over the various digit positions of the adder. Each detector circuit receives the digit pairs of the input operands of at least one adder position. The detection circuits indicate the beginning or the end of a carry ripple chain by testing the condition "both input digits zero or both input digits one". Via a coder, the output signals of the detection circuits are combined in the form of group indicating signals, each of which corresponds to a predetermined distance between the digit positions. By means of the group indicating signals a clock circuit is controlled in such a manner that the operating time is limited to the time required for carry rippling.