Abstract: System for the input and output of data on a two wire system with a downhole well tool which has a system with sensor devices, a processor, a clock, a memory and a voltage/current communications device which are all powered by a d.c. battery. A phone jack and phone plug connection at the earth's surface enables an operator with a controller to input and output data to the well tool without disassembly and enables setting the clock in the well tool to a selected real time value. This enables synchronization of real time values of data recordings for different tools.

Abstract: A self-contained, down hole powered electrical system in which a well tool microprocessor and circuitry can be programmed from an external microprocessor and verified as to functional capabilities and data can be retrieved from the tool by use of a current and voltage encoded binary system. Further, the system includes an alarm system for verifying the operation of the tool.

Abstract: A self-contained, down hole powered electrical system in which the tool has nonvolatile memory means which are independent of applied power thereby permitting the power to the system to be turned off between sampling and further including a system for reentering data to nonvolatile memories for retention during high temperature operations.