Abstract: A lateral insulated gate bipolar transistor comprises a p layer and a p.sup.+ layer provided apart from each other and extending from a surface of an n.sup.- layer into the n.sup.- layer, an n.sup.+ layer provided extending from a surface of the p layer into the p layer, a first main electrode provided in ohmic contact with the n.sup.+ layer and the p layer, a second main electrode provided in ohmic contact with the p.sup.+ layer, and a control electrode provided through an insulating film on the n.sup.+ layer, the p layer and the n.sup.- layer on the side of the first main electrode away from the second main electrode.

Abstract: A semiconductor device has a first diode having a pn junction and a second diode having a combination of a Schottky barrier and a pn junction in a current-passing direction provided side by side in a direction perpendicular to the current-passing direction. When a forward current with a current density J.sub.F is passed into the second diodes, the relation ##EQU1## is established in a forward voltage V.sub.F range of 0.1 (V) to 0.3 (V), where k represents the Boltzmann constant, T represents the absolute temperature, and q represents the quantity of electron charges.

Abstract: A computer file system, in which directory files and real files are organized in a tree structure, includes data items which are recorded in a high-ranking directory file in the tree structure, a high-ranking file management table which records file management data indicative of the assignment relation with low-ranking directory files or real files created below the high-ranking directory file, and a low-ranking file management data which is stored in any of the low-ranking directory files and indicative of the assignment relation between the low-ranking directory file and other low-ranking directory files or real files. The system further includes an assignment relation copy device which copies the file management data of a high-ranking or low-ranking file management table indicative of the assignment relation between the high-ranking or low-ranking directory files or real files into another high-ranking or low-ranking file management table.