Японский язык и компьютеры: вопросы адаптации и ввода текста

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In relation to the Japanese language and computers many adaptation issues arise, some unique to Japanese and others common to languages which have a very large number of characters. The number of characters needed in order to write in English is quite small, and thus it is possible to use only one byte (28=256 possible values) to encode each English character. However, the number of characters in Japanese is many more than 256 and thus cannot be encoded using a single byte Japanese is thus encoded using two or more bytes, in a so called "double byte" or "multi byte" encoding. Problems that arise relate to transliteration and romanization, character encoding, and input of Japanese text.

Written Japanese uses several different scripts: kanji (Chinese characters), 2 sets of kana (phonetic syllabaries) and roman letters. While kana and roman letters can be typed directly into a computer, entering kanji is a more complicated process as there are far more kanji than there are keys on most keyboards. To input kanji on modern computers, the reading of kanji is usually entered first, then an input method editor (IME), also sometimes known as a front end processor, shows a list of candidate kanji that are a phonetic match, and allows the user to choose the correct kanji. More advanced IMEs work not by word but by phrase, thus increasing the likelihood of getting the desired characters as the first option presented. Kanji readings inputs can be either via romanization (rōmaji nyūryoku, ) or direct kana input (kana nyūryoku, ). Romaji input is more common on PCs and other full size keyboards (although direct input is also widely supported), whereas direct kana input is typically used on mobile phones and similar devices – each of the 10 digits (1–9,0) corresponds to one of the 10 columns in the gojūon table of kana, and multiple presses select the row. There are two main systems for the romanization of Japanese, known as Kunrei shiki and Hepburn; in practice, "keyboard romaji" (also known as wāpuro rōmaji or "word processor romaji") generally allows a loose combination of both. IME implementations may even handle keys for letters unused in any romanization scheme, such as L, converting them to the most appropriate equivalent. With kana input, each key on the keyboard directly corresponds to one kana. The JIS keyboard system is the national standard, but there are alternatives, like the thumb shift keyboard, commonly used among professional typists.

Japanese can be written in two directions. Yokogaki style writes left to right, top to bottom, as with English. Tategaki style writes first top to bottom, and then moves right to left. To compete with Ichitaro, Microsoft provided several updates for early Japanese versions of Microsoft Word including support for downward text, such as Word 5.0 Power Up Kit and Word 98. QuarkXPress was the most popular DTP software in Japan in 1990s, even it had a long development cycle. However, due to lacking support for downward text, it was surpassed by Adobe InDesign which had strong support for downward text through several updates. At present, handling of downward text is incomplete. For example, HTML has no support for tategaki and Japanese users must use HTML tables to simulate it. However, CSS level 3 includes a property "writing mode" which can render tategaki when given the value "vertical rl" (i. e. top to bottom, right to left). Word processors and DTP software have more complete support for it.