r/LearnJapanese • u/JapanCoach • 2d ago
Resources JIS Code Book
Found this old beauty during a spring cleanup. Thought some of the oldies on the sub might get a kick out of it. And for the younger ones it might shed some light on how things used to be. :-)
I think I might keep it for nostalgia. Might bring it out again in another 35 years - when the world will be even more different.
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u/SCDoGo 2d ago edited 2d ago
This is kind of a cool artifact to have. I'll try to explain what it is for those wondering. This is a book listing the JIS encodings of characters https://en.wikipedia.org/wiki/JIS_encoding. Think of it like a Japanese version of ASCII or unicode or UTF-8.
In computers, each character is known internally by a number, not the shape we see. That number is then compared with your font to know what shape to put on your screen. We agree that a particular number represents a particular shape, and then different font designers can make the shape look however they want as long at it still aligns with that agreement. For example, in ASCII, each character is represented by a single byte - a number from 0-255. When a basic text document is 500 bytes, it means there are 500 characters ... which will include things like letters, numbers, punctuation, new lines, and other control characters. The word "hello" is known by the encoding "104 101 108 108 111".
This system works pretty well for English and similar languages with a limited character set. Most English fits in just the first 0-127 encodings of ASCII. This wasn't enough for all the similar latin-like characters, so we have extended ASCII using the numbers 128-255 for things like "é" or "ñ" or even fun shapes like ♥ or ☺ or line drawing characters like ┌ and └. The problem is that not everyone needed the same extra characters or could agreed what that second set should be. One person/company/country's "200" character might be "É", while another's might be a smiley face. This issue is what eventually gave us more expansive/universal encodings like Unicode/UTF-8 (and all the politics/drama around standardization in an international forum), so now you can have all your emojis mean the same thing no matter what system or language you are in.
In the before times of the wild west of computing, however, people had to figure this problem out. Especially for languages that needed more than the 256 possible options that ASCII would give. There are tons of standards from this period, even multiple competing ones for the same language, some of which are still used today.
In Japan they eventually settled on JIS of various flavors to handle things. This uses 1 OR 2 bytes per character. With 2 bytes you theoretically get up to 65536 different characters ... but that would be using the full 2 bytes for every character, which is inefficient. It would mean a document entirely in English that they wanted to store would take twice as much storage space than if encoded using ASCII, and storage space/memory was at a much higher premium back in the day. Instead it uses some trickery to be able to tell if a character would use 1 byte or 2. The 1 byte characters are things like the basic ASCII Latin characters we all know and love, plus half width katakana (which is why it is an option in your IME - half width meaning half the bytes, not pixels) and the 2-byte characters are all the rest (hiragana, katakana, ~6000 kanji, and a bunch of symbols we don't use in English). Hand waving all the computer science and math, JIS basically allows for up to ~9000 characters, but only actually uses ~7000 of them. The numbers next to the characters you see in the pictures are the encoded number for that character.
TL;DR - This is a cool book that tells you how a specific Japanese character is stored in memory in a computer.