Abstract: An optical recording medium able to reproduce address information during seeking in which an optical head moves between tracks, to increase seek speed, to improve recording/reproduction speed and to obtain a good header reproducing signal is achieved by that the concave portions or convex portions constituting a reproducing signal in seeking reproduced even during seek and/or constituting a timing signal for writing a header signal are connected to each other in a direction orthogonal to the tracks, when these concave portions and/or convex portions are placed in positions equivalent to each other in the adjacent tracks.

Abstract: A compound semiconductor device including a substrate; a first epitaxial layer formed on the substrate, the first epitaxial layer having an impurity concentration of 1.times.10.sup.15 .ltoreq.p.ltoreq.1.times.10.sup.16 (cm.sup.-3); and a second epitaxial layer formed on the first epitaxial layer for allowing travel of two-dimensional electrons, the second epitaxial layer having an impurity concentration of n.ltoreq.1.times.10.sup.14 (cm.sup.-3) and p.ltoreq.1.times.10.sup.14 (cm.sup.-3). With the device disclosed, it is difficult for a short channel effect due to a reduction in gate length to occur, thereby ensuring high characteristics of the compound semiconductor device.

Abstract: A method for manufacturing a semiconductor device, comprising the steps of forming a first resist layer, an intermediate layer and a second resist layer sequentially on a substrate; forming an aperture by removing a portion of the second resist layer where a T-shaped gate is to be later formed; over-etching a portion of the intermediate layer opposed to the aperture thereby forming in the intermediate layer an aperture larger than the first-mentioned aperture; and forming, in the first resist layer, an aperture which is smaller than the aperture in the second resist layer which is positioned inside thereof. Due to the combination of such successive steps, the lift-off process required to form a desires T-shaped gate can be substantially improved.

Abstract: Ignition timing of an internal combustion engine of an automotive vehicle is automatically adjusted by idling the engine with a distributor whose coil terminal and spark plug terminals are disconnected from ignition circuit and detecting an spurious ignition signal for a specified cylinder from the distributor. The distributor is turned with respect to the engine through an angle in accordance with a difference between a rotated angle of the crankshaft of the engine from a detection of the spurious ignition signal to a provision of a top dead center signal and a predetermined angle of the crankshaft for an expected ignition timing.