A recording instrument for use in ocean depths and like remote locations and adapted to provide meaningful readings of temperatures and pressure, for example, at such locations over a long period of time without attendance. Analog signals from transducers, which indicate the level of the thing-to-be-measured, are processed to give an averaged digital signal that is then stored on a magnetic tape. The system is battery powered. The instrument detailed is for use at ocean depths where the instrument housing and attachment to a mooring line are of particular importance.

The acceptance of all events and the processing of such events without lock-out in a multiple input data processing system is achieved by a random action event switching technique. Processing of all events in order of arrival is accomplished by providing an input line for each system input on which the priority of the received event is registered with the resolution of the switch timing clock. Events arriving on other lines during the same time resolution element are processed with equal priority but with identity preserved. At the end of each time interval accumulated events are switched to one of a multiplicity of event holding lines, there being fewer event holding lines than input lines, and the input lines are cleared to receive subsequently arriving events. Event holding lines are filled in selected sequence and are switched to the data system main processor for read-out according to the priority of arrival of the events they hold and in response to main processor availability signals.

Apparatus for increasing the seismic data storage capacity of magnetic tape. A pair of storage registers store a sequential pair of digitized seismic data samples. A subtractor coupled to these two registers provides an output equal to the difference between the two stored samples. A decoder and a set of gates couples the difference word serially to a bit comparator starting with the most significant bit. The first logical "1" which is encountered and all the lower order bits of the same word are serially coupled to and written in a read/write memory. The decoder and gates cause a "0" to be written in a second read/write memory at the beginning of each data word, and "1's" to be written in addresses corresponding to the data written in the first read/write memory. The data in the read/write memories are addressed for reading by a read/address counter, which is incremented by an incremental shaft encoder on a drive motor of a tape recorder. An up-down counter continuously monitors the difference between the number of bits written into the read/write memories and the number read from the memories and serially recorded by the tape recorder. The output of the up-down counter is used to control tape recorder motor speed.

A system is disclosed adapted to be carried on board a vehicle, such as a heavy duty truck operating on an interstate basis, wherein various operational and reference parameters of the vehicle, such as, the State of operation, mileage, fuel consumed, fuel purchased and time periods, are monitored and are recorded onto a recording medium, such as a tape cassette, which is removable from the system at the end of a trip, with the data recorded thereon being usable to produce a printout of the monitored parameters.