Abstract: A compressor piston divides a first compartment into two compression chambers, while a hammer piston divides a second compartment into two drive chambers, each of the compression chambers being connected to a respective one of the drive chambers to form a closed fluid system wherein reciprocation of the compressor piston causes cyclic compression and expansion of the fluid in the compression chambers and thus in the drive chambers, to effect a cyclic impacting of the hammer piston with a bit adapter connected to the drill bit. A mud motor rotates a shaft to drive an oscillator which reciprocates the compressor piston. The oscillator can comprise roller elements in the compressor piston in engagement with canted grooves in the shaft. While drilling mud drives the motor and then passes downwardly to flush the drill bit and the borehole, the drilling mud is isolated from the closed fluid system.

Abstract: This adjunct processor arrangement performs a centralized call screening function to provide computer port access security. Every call origination in the telephone switching system from a calling party to a protected computer port is interdicted by the telephone switching system and routed to the adjunct processor. The calling party receives a series of prompts from the adjunct processor to provide identification information, such as login, password, and voiceprint information. The adjunct processor validates the identity of the calling party using this identification indicia and initiates a callback operation. The adjunct processor disconnects the calling party from the connection, calls the calling party back and then uses the data call transfer capability of the telephone switching system to connect the calling party to the computer.