||The ISTUK deep drill was developed in 1978-1980. The drill is mechanical. The cuttings are sucked from the bits into storage chambers in the drill, and brought to the surface with each core increment (typically 2.4m in length). Because the actual drilling time is a fraction of the total run time, with most of the time spent going up and down in the drill hole, much emphasis has been placed on reducing the friction in the hole and in reducing the time consumed on the surface. In order to simplify the drilling operation, the steel drill cable uses only one wire with the armour acting as power return. Also, to enhance the reliability of the drilling, most drill control tasks are taken care of by a down borehole processor. The drill was first used during 1979-1981 at Dye-3 in south Greenland, and lately during 1990-1992 at Summit, central Greenland. The Summit drill is physically the same as the Dye-3 drill however, the motor section has been replaced, as have the high-pressure gaskets. The cutters and the core catchers are basically the same, but the angles have been changed slightly. The electronics are new, although the functions performed are unchanged. The winch and the tilting tower are both of new construction and use an electronic variable frequency inverter to drive a standard 3-phase electrical motor. A load transducer is built into the center bolt of the sheave in the drill tower. The readout from this transducer indicates the cable load with high resolution.