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kkeeyybbooaarrdd ttaabblleess -- Technical Information
The COHERENT device-driver nnkkbb supports industry-standard 83-, 101-, and
102-key AT-protocol keyboards attached as the computer console.
nnkkbb lets you define both the layout of the keyboard and the values returned
by function keys. You can change layout and function-key bindings by using
the special keyboard mapping programs kept in directory /ccoonnff/kkbbdd. This
directory contains the C source code for the mapping tables, as well as a
MMaakkeeffiillee that helps you rebuild the mapping programs.
Before you begin to write or modify an existing keyboard table, be sure to
read throroughly this article and the Lexicon article on nnkkbb. If you do
not, you may foul up the keyboard so thoroughly that it will not work well
enough for you to undo your mistake!
_O_p_e_r_a_t_i_o_n_a_l _O_v_e_r_v_i_e_w
The device driver nnkkbb provides the system's portion of the interface to the
console keyboard. It handles hardware-specific details, such as
initializing the keyboard and internal state, handling keyboard interrupts,
processing key scan codes, and queueing characters.
The user half of the keyboard interface is provided by a set of stand-alone
utilities. With these, you can program the nnkkbb driver via specialized
iiooccttll() calls. These utilities differ from each other only in the keyboard
binding or mapping tables each uses. You can re-construct the interface to
the nnkkbb driver by modifying a keyboard-mapping file and then using a
support module to link that file to the driver.
The keyboard-mapping file is a C program that consists of initialized
tables and strings. In addition, several header files provide the scan
codes and other constants required for the key tables. This format makes
the file easy to edit, and also lets you enter characters in several
different formats.
The support module, in turn, performs several tasks. These include
scanning the keyboard-mapping file for errors, reformatting the table for
use by the device driver, and passing the reformatted table to the driver.
_K_e_y _M_a_p_p_i_n_g _F_i_l_e_s
By convention, directory /ccoonnff/kkbbdd contains the keyboard-mapping files,
executables, and a MMaakkeeffiillee that you use to construct the executables from
the corresponding source files.
A keyboard-mapping source file consists primarily of three data structures
that you must modify to support a given keyboard mapping. The first, and
simplest, of the structures is ttbbll_nnaammee. This is a character string that
describes the keyboard. For example, the stock 101-key US AT keyboard
mapping file /ccoonnff/kkbbdd/uuss.cc initializes this string to:
"U.S. AT keyboard table"
The second data structure, kkbbttbbll, is an array of key-mapping entries. It
has one entry (or row) for each possible key location. Each entry in this
structure consists of 11 fields, which hold, respectively, the key number,
nine possible mapping values, and a mode field. The following example is
for physical key location 3 from key-mapping source file
/ccoonnff/kkbbdd/bbeellggiiaann.cc:
{ K_3, 0x82, '2', none, none, 0x82, '2', '~', none, '~', O|T },
Field 1 contains the _s_c_a_n _c_o_d_e _s_e_t _3 code value for the desired key.
Header file <ssyyss/kkbbssccaann.hh> contains symbolic constants of the form KK__n_n_n
that map the AT keyboard's _p_h_y_s_i_c_a_l key number _n_n_n to the corresponding
scan code set 3 value generated by the keyboard. In the above example, KK_33
corresponds to key location three.
Fields 2 through 10 contain the key mappings corresponding to the following
shift states, as follows:
2 base or unshifted
3 SSHHIIFFTT
4 CCOONNTTRROOLL
5 CCOONNTTRROOLL+SSHHIIFFTT
6 AALLTT
7 AALLTT+SSHHIIFFTT
8 AALLTT+CCOONNTTRROOLL
9 AALLTT+CCOONNTTRROOLL+SSHHIIFFTT
10 AALLTT_GGRRAAPPHHIICC
For ``regular'' keys, the values for these nine fields are eight-bit
characters; for ``function'' or ``shift'' keys, they are special values.
The symbolic constant nnoonnee indicates that you want no output when the key
is pressed in the specified shift state.
In the case of a function key, the value specified is the number of the
desired function key. Header file <ssyyss/kkbb.hh> defines a set of symbolic
constants of the form ff_n, where _n is the desired function key number. You
should use these constants; they will improve the readability of your code,
and they will protect your keyboard mapping source files from any future
changes in the structure of the keyboard driver.
In the case of a ``shift'' key, all nine entries must be identical and must
consist of one of the following symbolic constants: ssccrroollll, nnuumm, ccaappss,
llaalltt, rraalltt, llsshhiifftt, rrsshhiifftt, llccttrrll, rrccttrrll, or aallttggrr. These are defined in
the <ssyyss/kkbb.hh> header file. Note that 83-key XT-layout keyboards only have
one ``control'' and ``alt'' key, so not all shift-key combinations may be
possible on your target keyboard.
The last (11th) field in the key entry is the ``mode'' field. The
following symbolic constants specify the mode of the current key:
CC The ccaappss lloocckk key affects this key.
FF The specified key is a ``function'' or special key. The value of all
mapping entries must name function keys. See header file <kkbb.hh> for a
list of predefined function keys.
MM Make: use this mode with keys that do not repeat. Note that
accidentally using this mode with ``shift'' keys will stop you from
being able to ``unshift'' upon releasing the key!
MMBB Make/Break: use this mode with ``shift'' keys.
NN The nnuumm lloocckk key affects this key.
OO The specified key is ``regular'' and requires no special processing.
SS The specified key is a ``shift'' or ``lock'' key. Note that all
mapping entries for a given key must be identical for a ``shift'' or
``lock'' key to work correctly.
TT Typematic: this type is usually associated with a ``regular'' key.
TTMMBB Typematic/Make/Break.
The above example specifies a mode field of OO|TT, which corresponds to a
``regular'' key with Typematic repeat, and no special handling of the
``lock'' keys.
The last data structure, ffuunnkkeeyy, consists of an array of function-key
initializers, one per function key. The initializers are simple quoted
character strings delimited by either hexadecimal value 00xxFFFF, octal value
\337777, or symbolic constant DDEELLIIMM. Note that any other value can be used as
part of a function-key binding. Function keys are numbered starting at
zero. By convention, function key 0, when enabled, reboots your computer.
For traditional reasons, this function key is usually bound to the key
sequence <ccttrrll><aalltt><ddeell>.
Function keys are useful not only in the classic sense of the programmable
function keys on the keyboard, but also as a general purpose mechanism for
binding arbitrary length character sequences to a given key. For example,
physical key location 16 is usually associated with the <ttaabb> and <bbaacckk
ttaabb> on the AT keyboard; and /ccoonnff/kkbbdd/uuss.cc sets the key mapping table
entry for key 16 as follows:
{ K_16, f42, f43, none, none, f42, f43, none, none, none, F|T },
For traditional reasons, the <bbaacckk ttaabb> key outputs the sequence <eesscc>[ZZ
whereas the <ttaabb> key simply outputs the horizontal-tab character <ccttrrll-II>.
Because at least one of the mapping values for this key is more than one
character long, the key must be defined as a ``function'' key and all
entries for the the key must correspond to function-key numbers. In this
example, function key number 42 was chosen for <ttaabb>, and function key
number 43 was chosen for <bbaacckk ttaabb>. The constant nnoonnee indicates that you
want no output when the key is pressed in the specified shift state. The
corresponding ffuunnkkeeyy initialization entries for function keys ff4422 and ff4433
are as follows:
/* 42 */ "\t\377", /* Tab */
/* 43 */ "\033[Z\377", /* Back Tab */
We strongly recommend that you comment your function-key bindings.
You can also change function-key bindings via the command ffnnkkeeyy. This
command lets you temporarily alter one or more function-key mappings
without changing your key-mapping sources.
_B_u_i_l_d_i_n_g _N_e_w _B_i_n_a_r_i_e_s
After you have modified an existing keyboard-mapping table, use the
following commands to rebuild the corresponding executables:
cd /conf/kbd
su root
make
If you have created a new keyboard mapping table, you must edit
/ccoonnff/kkbbdd/MMaakkeeffiillee. Duplicate an existing entry from the MMaakkeeffiillee, and
change the duplicated name to match the name of your new keyboard-mapping
table. After you have finished your editing, build an executable from your
source file by simply executing the above series of commands.
To load your new keyboard table, simply type the name of the executable
that corresponds to your keyboard-mapping file. For example, if you just
built executable ffrreenncchh from source file ffrreenncchh.cc, type the following
command:
/conf/kbd/french
If the keyboard-support module finds an error, it will print an appropriate
message. If it finds no errors, it will update the internal tables of the
nnkkbb keyboard driver, reprogram the keyboard, and print a message of the
form:
Loaded French AT keyboard table
_E_x_a_m_p_l_e_s
Prior to the release of the 101- and 102-key, enhanced-layout AT keyboards,
the <ccttrrll> key was positioned to the left of `A' key. Most terminals also
locate the <ccttrrll> key there. The first example shows how to swap the left
<ccttrrll> key and the <ccaappss-lloocckk> key on a 101- and 102-key keyboard. The
<ccaappss-lloocckk> key is physical key 30, whereas the left <ccttrrll> key is physical
key 58. Their respective entries in file /ccoonnff/kkbbdd/uuss.cc source file are as
follows:
{ K_30, caps, caps, caps, caps, caps, caps, caps, caps, caps, S|M },
{ K_58, lctrl,lctrl,lctrl,lctrl,lctrl,lctrl,lctrl,lctrl,lctrl, S|MB },
Note that the <ccaappss-lloocckk> key is defined with mode MM as it is a ``lock''
key. The keyboard will interrupt only on key depressions, because
releasing a ``lock'' key has no effect. The left <ccttrrll> key is defined
with mode MMBB as it is a ``shift'' key. The keyboard generates an interrupt
on both key depression and key release, because the driver must track the
state of this key.
To swap the aforementioned keys, simply change all occurrences of ccaappss to
llccttrrll and vice-versa, as well as swapping the mode fields. After making
the changes, the entries now appear as:
{ K_30, lctrl,lctrl,lctrl,lctrl,lctrl,lctrl,lctrl,lctrl,lctrl, S|MB },
{ K_58, caps, caps, caps, caps, caps, caps, caps, caps, caps, S|M },
The second example converts a 101- or 102-key keyboard table to support an
XT-style 83-key keyboard layout. The following section summarizes the
``typical'' differences found when comparing the two keyboard layouts.
Needless to say, given the extreme variety in keyboard designs, your
mileage may vary.
_L_o_c_a_t_i_o_n _1_0_1/_1_0_2 _V_a_l_u_e _8_3-_k_e_y _V_a_l_u_e _C_o_m_m_e_n_t_s
14 nnoonnee Various Keyboard-specific
30 ccaappss llccttrrll
58 llccttrrll llaalltt
64 rrccttrrll ccaappss
65 nnoonnee FF22 Function Key
66 nnoonnee FF44 Function Key
67 nnoonnee FF66 Function Key
68 nnoonnee FF88 Function Key
69 nnoonnee FF1100 Function Key
70 nnoonnee FF11 Function Key
71 nnoonnee FF33 Function Key
72 nnoonnee FF55 Function Key
73 nnoonnee FF77 Function Key
74 nnoonnee FF99 Function Key
90 nnuumm EEsscc
95 / nnuumm
100 * ssccrroollll
105 - nnoonnee <SSyyssRReeqq> not used
106 + *
107 nnoonnee -
108 <EEnntteerr> +
110 eesscc nnoonnee Not on XT layout
112-123 FF11-FF1122 nnoonnee Not on XT layout
124 nnoonnee nnoonnee <PPrrttSSccrr> not used
125 ssccrroollll nnoonnee Not on XT layout
126 nnoonnee nnoonnee <PPaauussee> not used
_S_e_e _A_l_s_o
ddeevviiccee ddrriivveerrss, ffnnkkeeyy, kkbb.hh, nnkkbb
_N_o_t_e_s
Key 14, if used, varies considerably among keyboard models.
The location of the key that contains characters `\' and `|' varies among
101-key US-layout keyboards.
When designing keyboard tables for keyboards that use the AALLTT_GGRRAAPPHHIICC shift
key, for reasons of backwards compatibility you should allow the use of
combination shift AALLTT+CCTTRRLL as a synonym for AALLTT_GGRRAAPPHHIICC.
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