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keyboard - how to type characters


Keyboards are idiosyncratic. The differing conventions of host operating systems make them more so for Inferno. In all implementations, it should be obvious how to type ordinary ASCII characters, backspace, tab, escape, and newline. When typing into the Inferno environment, the key labelled Return or Enter generates a newline (0x0A); if there is a key labelled Line Feed, it generates a carriage return (0x0D); Inferno eschews CRLFs. All control characters are typed in the usual way; in particular, control-J is a line feed and control-M a carriage return.

In native mode, on the PC and some other machines, the following extra conventions might also be used. The key labelled Caps Lock acts as an additional control key. The character erase key generates backspace. The key labelled Del or Delete generates the delete character (0x7F). The plethora of function keys generate values in the Unicode user-defined space, as defined by /include/keyboard.h and /module/keyboard.m. They are fitfully supported by applications, but Page Up and Page Down are often understood by Tk applications.

Characters in Inferno are runes (see utf(6)). Any rune can be typed using a compose key followed by several other keys. The compose key is implementation-dependent, and is also generally near the lower right of the main key area: either Alt key on the PC, and in X11 implementations, whatever X11 regards as Alt or Meta. After typing the compose key, type a capital X and exactly four hexadecimal characters (digits and a to f) to type a single rune with the value represented by the typed number. There are shorthands for many characters, comprising the compose key followed by a two- or three-character sequence. There are several rules guiding the design of the sequences, as illustrated by the following examples. The full list is too long to repeat here, but is contained in the file /lib/keyboard in a format suitable for grep(1).

A repeated symbol gives a variant of that symbol, e.g., ?? yields ¿.

ASCII digraphs for mathematical operators give the corresponding operator, e.g., <= yields <=.

Two letters give the corresponding ligature, e.g., AE yields Æ.

Mathematical and other symbols are given by abbreviations for their names, e.g., pg yields ¶.

Chess pieces are given by a w or b followed by a letter for the piece (k for king, q for queen, r for rook, n for knight, b for bishop, or p for pawn), e.g., wk for a white king.

Greek letters are given by an asterisk followed by a corresponding latin letter, e.g., *d yields DELTA.

Cyrillic letters are given by an at sign followed by a corresponding latin letter or letters, e.g., @ya yields я.

Script letters are given by a dollar sign followed by the corresponding regular letter, e.g., $F yields ℱ.

A digraph of a symbol followed by a letter gives the letter with an accent that looks like the symbol, e.g., ,c yields ç.

Two digits give the fraction with that numerator and denominator, e.g., 12 yields ½.

The letter s followed by a character gives that character as a superscript, e.g., s1 yields ¹.

Sometimes a pair of characters give a symbol related to the superimposition of the characters, e.g., cO yields ©.

A mnemonic letter followed by $ gives a currency symbol, e.g., l$ yields £.

Note the difference between ß (ss) and µ (micron) and the Greek BETA and MU.


sorted table of characters and keyboard sequences


acme(1), wm-brutus(1), intro(1), unicode(1), cons(3), utf(6), kbdputc(10.2)

KEYBOARD(6 ) Rev:  Tue Mar 31 02:42:38 GMT 2015