+
+
+The data from a keyboard comes mainly in the form of scancodes, +produced by key presses or used in the protocol with the computer. +( +Different codes are used by the keyboard +firmware internally, and there also exist several +sets of scancodes. +Here in this section we only talk about the default codes - those from +translated scancode set 2. Less common modes are discussed +below.) +Each key press and key release produces between 0 and 6 scancodes. +
+
Below I'll only mention the scancode for key press (`make'). +The scancode for key release (`break') is obtained from it +by setting the high order bit (adding 0x80 = 128). +Thus, Esc press produces scancode 01, Esc release +scancode 81 (hex). +For sequences things are similar: Keypad-/ gives e0 35 +when pressed, e0 b5 when released. Most keyboards will +repeat the make code (key down code) when the key repeats. Some will also +fake Shift down and Shift up events during the repeat. +
The keys PrtSc/SysRq and Pause/Break are special. +The former produces scancode e0 2a e0 37 +when no modifier key is pressed simultaneously, e0 37 +together with Shift or Ctrl, but 54 together with (left or right) Alt. +(And one gets the expected sequences upon release. But see +below.) +The latter produces scancode sequence +e1 1d 45 e1 9d c5 +when pressed (without modifier) and nothing at all upon release. +However, together with (left or right) Ctrl, one gets +e0 46 e0 c6, +and again nothing at release. It does not repeat. +
See +below for a report on keys +with a different behaviour. +
There are many reports of laptops with badly debounced key-up events. +Thus, unexpected key-up events should probably be regarded as not +unusual, and be ignored. Another source of key-up events without +preceding key-down can be the +fake shift. +
+
Most scancodes indicate a key press or release. +Some are used in the communication protocol. +
+
+
| +00 | Keyboard error - see ff |
| +aa | BAT (Basic Assurance Test) OK |
| +ee | Result of echo command |
| +f1 | Some keyboards, as reply to command a4:Password not installed |
| +fa | Acknowledge from kbd |
| +fc | BAT error or Mouse transmit error |
| +fd | Internal failure |
| +fe | Keyboard fails to ack, please resend |
| +ff | Keyboard error |
| + + |
Three common causes for keyboard error are: +(i) several keys pressed simultaneously, +(ii) keyboard buffer overflow, +(iii) parity error on the serial line used by keyboard +and keyboard controller for communication. +The error reported is ff in +scancode mode 1, +and 00 in scancode modes 2 and 3. +If translation is on, both 00 and ff +are translated as ff. +
Usually these codes have the protocol meaning. However, +they also occur as actual scancodes, especially when +prefixed by e0. +
+
The codes e0 and e1 introduce scancode sequences, +and are not usually used as isolated scancodes themselves +(but see +below). +
(The prefix e0 was originally used for the grey duplicates +of keys on the original PC/XT keyboard. These days e0 is +just used to expand code space. The prefix e1 used for +Pause/Break indicated that this key sends the make/break sequence +at make time, and does nothing upon release.) +
This, and the above, means that the values +00, 60, 61, 6e, 71, +7a, 7c, 7e, 7f +are unavailable to signify key presses (on a default keyboard). +Nevertheless they also occur as scancodes, see for example the +Telerate and +Safeway SW23 keyboards below. +
Also other prefixes occur, see +below. +
+Logitech uses an e2 prefix +for the codes sent by a pointing device integrated on the keyboard. +
+
+
The scancodes in translated scancode set 2 are given in hex. +Between parentheses the keycap on a US keyboard. +The scancodes are given in order, grouped according +to groups of keys that are usually found next to each other. +
00 is normally an error code +
01 (Esc) +
02 (1!), 03 (2@), 04 (3#), 05 (4$), +06 (5%E), 07 (6^), 08 (7&), +09 (8*), 0a (9(), 0b (0)), 0c (-_), +0d (=+), 0e (Backspace) +
0f (Tab), 10 (Q), 11 (W), 12 (E), +13 (R), 14 (T), 15 (Y), +16 (U), 17 (I), 18 (O), +19 (P), 1a ([{), 1b (]}) +
1c (Enter) +
1d (LCtrl) +
1e (A), 1f (S), 20 (D), 21 (F), +22 (G), 23 (H), 24 (J), 25 (K), +26 (L), 27 (;:), 28 ('") +
29 (`~) +
2a (LShift) +
2b (\|), on a 102-key keyboard +
2c (Z), 2d (X), 2e (C), 2f (V), +30 (B), 31 (N), 32 (M), 33 (,<), +34 (.>), 35 (/?), 36 (RShift) +
37 (Keypad-*) or (*/PrtScn) on a 83/84-key keyboard +
38 (LAlt), 39 (Space bar), +
3a (CapsLock) +
3b (F1), 3c (F2), 3d (F3), 3e (F4), +3f (F5), 40 (F6), 41 (F7), +42 (F8), 43 (F9), 44 (F10) +
45 (NumLock) +
46 (ScrollLock) +
47 (Keypad-7/Home), 48 (Keypad-8/Up), +49 (Keypad-9/PgUp) +
4a (Keypad--) +
4b (Keypad-4/Left), 4c (Keypad-5), +4d (Keypad-6/Right), 4e (Keypad-+) +
4f (Keypad-1/End), 50 (Keypad-2/Down), +51 (Keypad-3/PgDn) +
52 (Keypad-0/Ins), 53 (Keypad-./Del) +
54 (Alt-SysRq) on a 84+ key keyboard +
55 is less common; occurs e.g. as F11 on a Cherry G80-0777 keyboard, +as F12 on a Telerate keyboard, +as PF1 on a Focus 9000 keyboard, and as FN on an IBM ThinkPad. +
56 mostly on non-US keyboards. It is often an unlabelled key
+to the left
+or
+to the right
+of the left Alt key.
+
+
+
57 (F11), 58 (F12) both on a 101+ key keyboard +
59-5a-...-7f are less common. +Assignment is essentially random. +Scancodes 55-59 occur as F11-F15 on the +Cherry G80-0777 keyboard. +Scancodes 59-5c occur on the +RC930 keyboard. +X calls 5d `KEY_Begin'. +Scancodes 61-64 occur on a +Telerate keyboard. +Scancodes 55, 6d, 6f, 73, 74, +77, 78, 79, 7a, 7b, +7c, 7e occur on the +Focus 9000 keyboard. +Scancodes 65, 67, 69, 6b +occur on a +Compaq Armada keyboard. +Scancodes 66-68, 73 occur on the +Cherry G81-3000 keyboard. +Scancodes 70, 73, 79, 7b, 7d +occur on a +Japanese 86/106 keyboard. +
Scancodes f1 and f2 occur on +Korean keyboards. +
+
Apart from the Pause/Break key, that has an escaped sequence starting +with e1, the escape used is e0. Often, the codes +are chosen in such a way that something meaningful happens when +the receiver just discards the e0. +
+
| +e0 1c (Keypad Enter) | 1c (Enter) | |
| +e0 1d (RCtrl) | 1d (LCtrl) | |
| +e0 2a (fake LShift) | 2a (LShift) | |
| +e0 35 (Keypad-/) | 35 (/?) | |
| +e0 36 (fake RShift) | 36 (RShift) | |
| +e0 37 (Ctrl-PrtScn) | 37 (*/PrtScn) | |
| +e0 38 (RAlt) | 38 (LAlt) | |
| +e0 46 (Ctrl-Break) | 46 (ScrollLock) | |
| +e0 47 (Grey Home) | 47 (Keypad-7/Home) | |
| +e0 48 (Grey Up) | 48 (Keypad-8/UpArrow) | |
| +e0 49 (Grey PgUp) | 49 (Keypad-9/PgUp) | |
| +e0 4b (Grey Left) | 4b (Keypad-4/Left) | |
| +e0 4d (Grey Right) | 4d (Keypad-6/Right) | |
| +e0 4f (Grey End) | 4f (Keypad-1/End) | |
| +e0 50 (Grey Down) | 50 (Keypad-2/DownArrow) | |
| +e0 51 (Grey PgDn) | 51 (Keypad-3/PgDn) | |
| +e0 52 (Grey Insert) | 52 (Keypad-0/Ins) | |
| +e0 53 (Grey Delete) | 53 (Keypad-./Del) | |
| + + |
These escaped scancodes occur only on 101+ key keyboards. +The +Microsoft keyboard adds +
+
| +e0 5b (LeftWindow) |
| +e0 5c (RightWindow) |
| +e0 5d (Menu) |
| + + |
Other escaped scancodes occur - see below under the individual keyboards. +
+
The ten grey keys Insert, Home, PgUp, Delete, End, PgDn, +Up, Left, Down, Right are supposed to function regardless +of the state of Shift and NumLock keys. But for an old AT keyboard +the keypad keys would produce digits when Numlock was on or Shift +was down. Therefore, in order to fool old programs, +fake scancodes are sent: when LShift is down, and Insert is +pressed, e0 aa e0 52 is sent; +upon release of Insert e0 d2 e0 2a +is sent. In other words, a fake LShift-up and +fake LShift-down are inserted. +
If the Shift key is released earlier than the repeated key, +then a real Shift-up code occurs (without preceding fake Shift-down) +so that a program ignoring e0 would see one more Shift-up +than Shift-down. +
When NumLock is on, no fake Shifts are sent when Shift was down, +but fake Shifts are sent when Shift was not down. Thus, +with Numlock, if Insert is pressed, +e0 2a e0 52 is sent +and upon release e0 d2 e0 aa is sent. +The keyboard maintains a private NumLock mode, toggled when +NumLock is pressed, and set when the NumLock LED is set. +
In the same way, when Shift is down, the Grey-/ key produces +fake Shift-up and fake Shift-down sequences. However, it does +not react to the state of NumLock. The purpose of course is to +fool programs that identify Grey-/ with ordinary /, so that they +don't treat Shift-Grey-/ like Shift-/, i.e., ?. +
On a Toshiba notebook, the three Windows keys are treated like +the group of ten keys mentioned, and get fake shifts when +(left or right) Shift is down. They do not react to NumLock. +
+
On my 121-key +Nokia Data keyboard there are +function keys F1, ..., F24, where F1, ..., F12 send the expected codes +3b, ..., 58, and F13, ..., F24 send the same codes +together with the LShift code 2a. +Thus, F13 gives 2a 3b on press, +and bb aa on release. +Similarly, there are keys with added LCtrl code 1d. +But there are also keys with added fake shifts e0 2a. +
+Delorie +reports that the "Preh Commander AT" keyboard with additional F11-F22 keys +treats F11-F20 as Shift-F1..Shift-F10 and F21/F22 as Ctrl-F1/Ctrl-F2; the +Eagle PC-2 keyboard with F11-F24 keys treats those additional keys +in the same way. +
+
On some motherboards the LCtrl-LAlt-GreyPlus and LCtrl-LAlt-GreyMinus +switch Turbo mode on/off, respectively. For these, the motherboard +may generate the same scancode sequence when the Turbo button is +pushed: Turbo Switch (High->Low): +1d 38 4a ce b8 9d +and Turbo Switch (Low->High): +1d 38 4e ce b8 9d. +
Other peculiar combinations in this style include +LCtrl-LAlt-LShift-GreyMinus and LCtrl-LAlt-LShift-GreyPlus to turn +system cache off/on. +
If Green PC system power saving mode is enabled in AMIBIOS Setup, +the AMI MegaKey keyboard controller recognizes the combinations +Ctrl-Alt-\ (put the system into immediate power down mode), +Ctrl-Alt-[ (disable the Green PC power savings mode temporarily), +Ctrl-Alt-] (enables the Green PC power down mode). +
Thio Yu Jin <jin@singmail.com> complains that on his Toshiba 4010CDS
+the Ctrl-Alt-Shift-T key combination brings up the Toshiba user manual.
+(04 Mar 1999 - not April 1.)
+
+
+
+Microsoft recommends: "i8042-based keyboards should deploy the +following scan codes for power management buttons, i.e., POWER and SLEEP +buttons: +
+
| + | Set-1 make/break | Set-2 make/break |
| + | ||
| +Power | e0 5e / e0 de | e0 37 / e0 f0 37 |
| +Sleep | e0 5f / e0 df | e0 3f / e0 f0 3f |
| +Wake | e0 63 / e0 e3 | e0 5e / e0 f0 5e |
| + + |
The Power, Sleep, and Wake event scan codes are the i8042 equivalents +to the System Power Down, System Sleep, and System Wake Up HID usages". +
Many keyboards have Power/Sleep/Wake keys that have to be +activated by a fourth key (unlabeled, or labeled FN): pressing +one of these four keys does not produce any scancodes, but +when the FN key is pressed simultaneously, the Power/Sleep/Wake +keys give the codes listed above. +
+
+
Many keyboards have more keys and buttons than the standard ones. +Sometimes these additional keys produce scancode combinations +that were unused before. But on other keyboard such additional +keys do not produce any code at all, until some initializing +action is taken. +
Sometimes that action consists of writing some bytes to keyboard +registers. See, for example, the +IBM Rapid Access keyboard, and the +Omnibook keyboard. +
+
Some keyboards have additional LEDs, and in a few cases we know +how to manipulate those. +
The +Chicony keyboard needs command sequences +eb 00 xy, with +xy = 01 for the Moon LED and +xy = 02 for the zzZ LED. +
The +IBM EZ Button keyboard needs +command sequences eb 00 xy, with +xy = 01 for the Msg LED, +xy = 02 for the CD LED, +xy = 04 for the Power LED, +xy = 10 for the Talk LED, and +xy = 20 for the Message Waiting LED. +
The +IBM Rapid Access keyboard needs +command sequences eb 00 xy, with +xy = 04 for the Suspend LED and +xy = 20 for the Mute LED. +
The +IBM Rapid Access keyboard II needs +the command sequences eb 71 and eb 70 +to switch the Standby LED on and off. +
The +Logitech Internet Keyboard +has an additional amber LED. It is turned on by sending eb, +and then blinks about once a second. It is turned off again by ec. +
+
Laptops have no room for all nonsensical keys one usually find +on a regular keyboard. So, the number pad and other keys are +folded into the main part of the keyboard. A key without label, +or labelled FN is often used to modify the meaning of other keys. +This FN does not produce scancodes itself, it only modifies the +scancodes produced by other keys. +
+ +Neil Brown reports about his Dell Latitude D800 laptop that it has +five key combinations that do not produce proper break codes. +The five combinations FN+F2, FN+F3, FN+F10, FN+Down, FN+Up +(labelled Wireless, Brighter, Darker, Battery, CDEject) +produce make codes e0 08, e0 07, +e0 09, e0 05, e0 06, +respectively. The first three do not produce any break code. +The last two have a break code that is identical to the make code. +
+