Rubik's family cubes of all sizes Rubik's family cubes of all sizes The original Rubik's cube was a mechanical 3×3×3 cube puzzle invented in 1974 by the Hungarian sculptor and professor of architecture Ernő Rubik. Extensions of the Rubik's cube have been around for a long time and come in both hardware and software forms. The major extension have been the availability of cubes of larger size and the availability of the more complex cubes with marked centres. The properties of Rubik’s family cubes of any size together with some special attention to software cubes is the main focus of this article. Many properties are mathematical
D-3 (video) D-3 (video) D-3 is an uncompressed composite digital video videocassette format invented at NHK, and introduced commercially by Panasonic in 1991 to compete with Ampex's D-2. It uses half-inch metal particle tape at 83.88 mm/s (compare to D-2's 19 mm and 131.7 mm/s). Like D-2, the composite video signal is sampled at four times the color subcarrier frequency, with eight bits per sample. Four channels of 48 kHz 16–20 bit PCM audio, and other ancillary data, are inserted during the vertical blanking interval. The aggregate net (error corrected) bitrate of the format is 143 Mbit/s, and because the codec is