PS/2 Keyboard

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Contents

Overview

The PS/2 Keyboard is a device that talks to a PS/2 controller using serial communication. Ideally, each different type of PS/2 controller driver should provide some sort of standard/simple "send byte/receive byte" interface, and the PS/2 Keyboard driver would use this interface without caring about lower level details (like what type of PS/2 controller the device is plugged into).

The PS/2 Keyboard accepts commands and sends responses to those commands, and also sends scan codes indicating when a key was pressed or released.

Commands

A PS/2 Keyboard accepts many types of commands. A command is one byte. Some commands have data byte/s which must be sent after the command byte. The keyboard typically responds to a command by sending either an "ACK" (to acknowledge the command) or a "Resend" (to say something was wrong with the previous command) back.

The commands that a PS/2 Keyboard accepts are:

Command Byte Data Byte/s Meaning Response
0xED LED states:
Bit Use
0 ScrollLock
1 NumberLock
2 CapsLock

Note: Other bits may be used in international keyboards for other purposes (e.g. a Japanese keyboard might use bit 4 for a "Kana mode" LED).

Set LEDs 0xFA (ACK) or 0xFE (Resend)
0xEE None Echo (for diagnostic purposes, and useful for device removal detection) 0xEE (Echo) or 0xFE (Resend)
0xF0 Sub-command:
Value Use
0 Get current scan code set
1 Set scan code set 1
2 Set scan code set 2
3 Set scan code set 3
Get/set current scan code 0xFA (ACK) or 0xFE (Resend) if scan code is being set; 0xFA (ACK) then the scan code set number, or 0xFE (Resend) if you're getting the scancode
0xF2 None Identify keyboard 0xFA (ACK) followed by none or more ID bytes (see [| "Detecting Device Types"])
0xF3 Typematic byte:
Bit/s Meaning
0 to 4 Repeat rate (00000b = 30 Hz, ..., 11111b = 2 Hz)
5 to 6 Delay before keys repeat (00b = 250 ms, 01b = 500 ms, 10b = 750 ms, 11b = 1000 ms)
7 Must be zero
Set typematic rate and delay 0xFA (ACK) or 0xFE (Resend)
0xF4 None Enable scanning (keyboard will send scan codes) 0xFA (ACK) or 0xFE (Resend)
0xF5 None Disable scanning (keyboard won't send scan codes)

Note: May also restore default parameters

0xFA (ACK) or 0xFE (Resend)
0xF6 None Set default parameters 0xFA (ACK) or 0xFE (Resend)
0xF7 None Set all keys to typematic/autorepeat only (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xF8 None Set all keys to make/release (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xF9 None Set all keys to make only (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xFA None Set all keys to typematic/autorepeat/make/release (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xFB Scancode for key Set specific key to typematic/autorepeat only (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xFC Scancode for key Set specific key to make/release (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xFD Scancode for key Set specific key to make only (scancode set 3 only) 0xFA (ACK) or 0xFE (Resend)
0xFE None Resend last byte Previously sent byte or 0xFE (Resend)
0xFF None Reset and start self-test 0xAA (self-test passed), 0xFC or 0xFD (self test failed), or 0xFE (Resend)

Special Bytes

The keyboard sends bytes to the system. Some of these bytes have special meaning (e.g. responses from the commands above). The bytes the keyboard may send are:

Response Byte Meaning
0x00 Key detection error or internal buffer overrun
0xAA Self test passed (sent after "0xFF (reset)" command or keyboard power up)
0xEE Response to "0xEE (echo)" command
0xFA Command acknowledged (ACK)
0xFC and 0xFD Self test failed (sent after "0xFF (reset)" command or keyboard power up)
0xFE Resend (keyboard wants controller to repeat last command it sent)
0xFF Key detection error or internal buffer overrun

All other bytes sent by the keyboard are scan codes, where interpretation depends on the currently selected scan code set.

Driver Model

Command Queue and State Machine

Commands must be sent one at a time (e.g. if your driver is interrupt driven, you can't start sending a command within the IRQ handler because code outside the IRQ handler may be in the middle of sending a command). The command isn't completed until you've received an ACK for it. For example, if you send a command and the keyboard responds with "0xFE (resend)" then you have to send the command again (possibly limited to 3 retries before you give up and assume the keyboard doesn't support the command you're sending or there's been a hardware failure). Finally, sometimes you want to send several commands at once. For example, you might have a "reinitialise()" function that sets the scan code set, sets the typematic byte, sets the LEDs and enables scanning.

The simplest way to achieve this is for the driver to maintain a queue of commands. When you add a command to the queue, if the queue is empty you start sending the command; otherwise you append the command to the queue. When you receive an "0xFA (ACK)" from the keyboard you discard the command at the head of the queue and start sending the next command in the queue (if any). If you receive an "0xFE (Resend)" from the keyboard you can resend the command at the head of the queue.

The remainder of the driver should be a kind of state machine. The state machine moves into a different state when some commands are successfully completed, and when various bytes are received from the keyboard. For example, the driver might be in a default state and receive a break code that puts it into a "waiting for scan code after receiving break code" state. Then it might receive the first byte of a multi-byte scan code and shift to a "waiting for second byte of scan code after receiving break code" state. Finally it might receive the second/last byte of the scan code and then switch back to the default state.


Scan Code Sets, Scan Codes and Key Codes

A scan code set is a set of codes that determine when a key is pressed or repeated, or released. There are 3 different sets of scan codes. The oldest is "scan code set 1", the default is "scan code set 2", and there is a newer (more complex) "scan code set 3". Note: Normally on PC compatible systems the keyboard itself uses scan code set 2 and the keyboard controller translates this into scan code set 1 for compatibility. See "8042"_PS/2_Controller for more information about this translation.

Modern keyboards should support all three scan code sets, however some don't. Scan code set 2 (the default) is the only scan code set that is guaranteed to be supported. In theory (I haven't tried it) it should be possible to attempt to set scan code set 1 or scan code set 3, and then ask the keyboard which scan code it is currently using and see if it actually is using the requested scan code set. In this way it may be possible to determine which scan code sets the keyboard does support.

Scan codes themselves are sequences of one or more bytes. In some cases the sequence can be as many as 6 bytes (e.g. the "print screen" key in scan code set 1 generates the sequence 0xE1, 0x1D, 0x45, 0xE1, 0x9D, 0xC5 when pressed). This situation isn't really ideal. In general (for later processing) you want to convert these "one or more byte sequences" into a single integer that uniquely identifies a specific key, that can be used effectively in things like lookup tables (without having sparsely used "many GiB" lookup tables).

There is no standard for "key codes" - it's something you have to make up or invent for your OS. I personally like the idea of having an 8-bit key code where the highest 3 bits determine which row on the keyboard and the lowest 5 bits determine which column (essentially, the keyboard is treated as a grid of up to 8 rows and up to 32 columns of keys). Regardless of what you choose to use for your key codes, it should be something that is used by all keyboard drivers (including USB Keyboards) and could possibly also be used for other input devices (e.g. left mouse button might be treated as "key code 0xF1").

Basically, when the keyboard driver's state machine knows it has received a complete scan code, the next step is to convert the "one or more byte" scan code into a key code.


Key Codes, Key States and Key Mappings

Once you've got key codes, then next step is to keep track of which keys are currently being pressed. Imagine a computer game that uses the "WASD" keys for player movement - when the 'A' key is being pressed the player rotates clockwise. How does the game know if the 'A' key is currently being pressed? For this you'd want an array of flags, where each flag corresponds to a key code. There is a hidden bonus here - the keyboard driver itself can use the same "array of flags" to determine if a shift key, control key, alt key, etc is down, which can be quite useful when trying to convert the key code into an actual ASCII character or Unicode code point. For example, if the user presses the 'a' key then it might correspond to 'a' or 'A' (depending on capslock state and whether or not a shift key is being held down at the time) or might not correspond to a valid character at all (e.g. "control-a" or "alt-a").

Also note that (for example) a "WASD" game doesn't care if the keys are 'W', 'A', 'S' and 'D'. The game wants to know about keys in a specific "T-shaped" pattern on the left of the keyboard. If the keyboard happens to be something different, then the keys in the same location may be completely different (e.g. they would be '<', 'A', 'O' and 'E' keys on a Dvorak keyboard). This helps to explain my preference of having an 8-bit key code where the highest 3 bits determine which row on the keyboard and the lowest 5 bits determine which column (it's easy for a game to ask about the state of the third key on the left of the third row).

Once you're able to keep track of which keys are currently being pressed, the next step is to (attempt to) convert the key into an ASCII character or Unicode code point. At this point you need to know what type of keyboard the user has - is it "US QWERTY", or "French AZERTY", some form of Dvorak, or perhaps it's Arabic. To handle many different keyboard layouts, the keyboard driver needs to use tables to convert key codes into ASCII characters or Unicode code points; so that you only need to load a different "Key Mapping" table to support different keyboard layouts.

However, it's not quite that simple. Different keyboard layouts can have different meta keys, different status LEDs, etc. The Key Mapping table has to sort these differences out too. This is why you don't want to detect if the keyboard LEDs have changed earlier, but want to send the "set LEDs" command (if necessary) *after* you've found the entry for the key code in your key map table.

The final step of processing is to combine all relevant information into some sort of "keypress packet" structure, and send it to whomever (e.g. GUI). The entire "keypress packet" might include the following:

  • Unicode code point (if applicable)
  • Key code
  • Pressed/released flag
  • Various other key states (shift, alt, control, etc)
  • Various "toggle" states (CapsLock, ScrollLock, NumberLock, etc)

Scan Code Sets

As there are 3 different scan code sets, there are 3 different tables (one for each scan code set). Some of the scan codes correspond to extra keys that have been added over time and have become "relatively standard". To help keep track scan codes have been categorized and tagged in the tables below. The tags used are:

Tag Meaning
(keypad) A key that is on the numerics keypad (typically found on the right hand side of the keyboard).
(ACPI) A key that is part of the "ACPI" group of keys (typically found near the top of the keyboard). A lot of modern keyboards don't actually have these keys (if I remember right, they were fashionable in the late 1990's but have become less common since).

Note: Don't let the name fool you - these keys have nothing to do with ACPI at all and do behave like any other normal key (but could be useful for an OS that supports power management).

(multimedia) A key that is part of the multimedia group of keys (typically found near the top of the keyboard). A lot of modern keyboards do have at least some of these keys. Some of these keys are intended to be used for media players (volume control, play/pause, next track, previous track, etc), some are intended for web browsing (previous web page, next web page, refresh, favourites/bookmarks, etc), and and some are intended for launching applications (e.g. starting an email client, starting a calculator, opening "my computer", etc).


Scan Code Set 1

The following table shows which scan codes correspond to which keys when using scan code set 1 (for a "US QWERTY" keyboard only):

Scan code Key Scan code Key Scan code Key Scan code Key
0x01 escape pressed 0x02 1 pressed 0x03 2 pressed
0x04 3 pressed 0x05 4 pressed 0x06 5 pressed 0x07 6 pressed
0x08 7 pressed 0x09 8 pressed 0x0A 9 pressed 0x0B 0 (zero) pressed
0x0C - pressed 0x0D = pressed 0x0E backspace pressed 0x0F tab pressed
0x10 Q pressed 0x11 W pressed 0x12 E pressed 0x13 R pressed
0x14 T pressed 0x15 Y pressed 0x16 U pressed 0x17 I pressed
0x18 O pressed 0x19 P pressed 0x1A [ pressed 0x1B ] pressed
0x1C enter pressed 0x1D left control pressed 0x1E A pressed 0x1F S pressed
0x20 D pressed 0x21 F pressed 0x22 G pressed 0x23 H pressed
0x24 J pressed 0x25 K pressed 0x26 L pressed 0x27  ; pressed
0x28 ' (single quote) pressed 0x29 ` (back tick) pressed 0x2A left shift pressed 0x2B \ pressed
0x2C Z pressed 0x2D X pressed 0x2E C pressed 0x2F V pressed
0x30 B pressed 0x31 N pressed 0x32 M pressed 0x33 , pressed
0x34 . pressed 0x35 / pressed 0x36 right shift pressed 0x37 (keypad) * pressed
0x38 left alt pressed 0x39 space pressed 0x3A CapsLock pressed 0x3B F1 pressed
0x3C F2 pressed 0x3D F3 pressed 0x3E F4 pressed 0x3F F5 pressed
0x40 F6 pressed 0x41 F7 pressed 0x42 F8 pressed 0x43 F9 pressed
0x44 F10 pressed 0x45 NumberLock pressed 0x46 ScrollLock pressed 0x47 (keypad) 7 pressed
0x48 (keypad) 8 pressed 0x49 (keypad) 9 pressed 0x4A (keypad) - pressed 0x4B (keypad) 4 pressed
0x4C (keypad) 5 pressed 0x4D (keypad) 6 pressed 0x4E (keypad) + pressed 0x4F (keypad) 1 pressed
0x50 (keypad) 2 pressed 0x51 (keypad) 3 pressed 0x52 (keypad) 0 pressed 0x53 (keypad) . pressed
0x57 F11 pressed
0x58 F12 pressed
0x81 escape released 0x82 1 released 0x83 2 released
0x84 3 released 0x85 4 released 0x86 5 released 0x87 6 released
0x88 7 released 0x89 8 released 0x8A 9 released 0x8B 0 (zero) released
0x8C - released 0x8D = released 0x8E backspace released 0x8F tab released
0x90 Q released 0x91 W released 0x92 E released 0x93 R released
0x94 T released 0x95 Y released 0x96 U released 0x97 I released
0x98 O released 0x99 P released 0x9A [ released 0x9B ] released
0x9C enter released 0x9D left control released 0x9E A released 0x9F S released
0xA0 D released 0xA1 F released 0xA2 G released 0xA3 H released
0xA4 J released 0xA5 K released 0xA6 L released 0xA7  ; released
0xA8 ' (single quote) released 0xA9 ` (back tick) released 0xAA left shift released 0xAB \ released
0xAC Z released 0xAD X released 0xAE C released 0xAF V released
0xB0 B released 0xB1 N released 0xB2 M released 0xB3 , released
0xB4 . released 0xB5 / released 0xB6 right shift released 0xB7 (keypad) * released
0xB8 left alt released 0xB9 space released 0xBA CapsLock released 0xBB F1 released
0xBC F2 released 0xBD F3 released 0xBE F4 released 0xBF F5 released
0xC0 F6 released 0xC1 F7 released 0xC2 F8 released 0xC3 F9 released
0xC4 F10 released 0xC5 NumberLock released 0xC6 ScrollLock released 0xC7 (keypad) 7 released
0xC8 (keypad) 8 released 0xC9 (keypad) 9 released 0xCA (keypad) - released 0xCB (keypad) 4 released
0xCC (keypad) 5 released 0xCD (keypad) 6 released 0xCE (keypad) + released 0xCF (keypad) 1 released
0xD0 (keypad) 2 released 0xD1 (keypad) 3 released 0xD2 (keypad) 0 released 0xD3 (keypad) . released
0xD7 F11 released
0xD8 F12 released
0xE0, 0x1C (keypad) enter pressed 0xE0, 0x1D right control pressed
0xE0, 0x35 (keypad) / pressed
0xE0, 0x38 right alt (or altGr) pressed
0xE0, 0x47 home pressed
0xE0, 0x48 cursor up pressed 0xE0, 0x49 page up pressed 0xE0, 0x4B cursor left pressed
0xE0, 0x4D cursor right pressed 0xE0, 0x4F end pressed
0xE0, 0x50 cursor down pressed 0xE0, 0x51 page down pressed 0xE0, 0x52 insert pressed 0xE0, 0x53 delete pressed
0xE0, 0x5B left GUI pressed
0xE0, 0x5C right GUI pressed 0xE0, 0x5D "apps" pressed
0xE0, 0x9C (keypad) enter released 0xE0, 0x9D right control released
0xE0, 0xB5 (keypad) / released
0xE0, 0xB8 right alt (or altGr) released
0xE0, 0xC7 home released
0xE0, 0xC8 cursor up released 0xE0, 0xC9 page up released 0xE0, 0xCB cursor left released
0xE0, 0xCD cursor right released 0xE0, 0xCF end released
0xE0, 0xD0 cursor down released 0xE0, 0xD1 page down released 0xE0, 0xD2 insert released 0xE0, 0xD3 delete released
0xE0, 0xDB left GUI released
0xE0, 0xDC right GUI released 0xE0, 0xDD "apps" released
0xE0, 0x2A, 0xE0, 0x37 print screen pressed
0xE0, 0xB7, 0xE0, 0xAA print screen released
0xE1, 0x1D, 0x45, 0xE1, 0x9D, 0xC5 pause pressed


Note: There is no scan code for "pause key released" (it behaves as if it is released as soon as it's pressed)


Scan Code Set 2

The following table shows which "make" scan codes correspond to which keys when using scan code set 2 (for a "US QWERTY" keyboard only):

Scan code Key Scan code Key Scan code Key Scan code Key
0x01 F9 pressed 0x03 F5 pressed
0x04 F3 pressed 0x05 F1 pressed 0x06 F2 pressed 0x07 F12 pressed
0x09 F10 pressed 0x0A F8 pressed 0x0B F6 pressed
0x0C F4 pressed 0x0D tab pressed 0x0E ` (back tick) pressed
0x11 left alt pressed 0x12 left shift pressed
0x14 left control pressed 0x15 Q pressed 0x16 1 pressed
0x1A Z pressed 0x1B S pressed
0x1C A pressed 0x1D W pressed 0x1E 2 pressed
0x21 C pressed 0x22 X pressed 0x23 D pressed
0x24 E pressed 0x25 4 pressed 0x26 3 pressed
0x29 space pressed 0x2A V pressed 0x2B F pressed
0x2C T pressed 0x2D R pressed 0x2E 5 pressed
0x31 N pressed 0x32 B pressed 0x33 H pressed
0x34 G pressed 0x35 Y pressed 0x36 6 pressed
0x3A M pressed 0x3B J pressed
0x3C U pressed 0x3D 7 pressed 0x3E 8 pressed
0x41 , pressed 0x42 K pressed 0x43 I pressed
0x44 O pressed 0x45 0 (zero) pressed 0x46 9 pressed
0x49 . pressed 0x4A / pressed 0x4B L pressed
0x4C  ; pressed 0x4D P pressed 0x4E - pressed
0x52 ' pressed
0x54 [ pressed 0x55 = pressed
0x58 CapsLock pressed 0x59 right shift pressed 0x5A enter pressed 0x5B ] pressed
0x5D \ pressed
0x66 backspace pressed
0x69 (keypad) 1 pressed 0x6B (keypad) 4 pressed
0x6C (keypad) 7 pressed
0x70 (keypad) 0 pressed 0x71 (keypad) . pressed 0x72 (keypad) 2 pressed 0x73 (keypad) 5 pressed
0x74 (keypad) 6 pressed 0x75 (keypad) 8 pressed 0x76 escape pressed 0x77 NumberLock pressed
0x78 F11 pressed 0x79 (keypad) + pressed 0x7A (keypad) 3 pressed 0x7B (keypad) - pressed
0x7C (keypad) * pressed 0x7D (keypad) 9 pressed 0x7E ScrollLock pressed
0x83 F7 pressed
0xE0, 0x10 (multimedia) WWW search pressed 0xE0, 0x11 right alt pressed
0xE0, 0x14 right control pressed 0xE0, 0x15 (multimedia) previous track pressed
0xE0, 0x18 (multimedia) WWW favourites pressed
0xE0, 0x1F left GUI pressed
0xE0, 0x20 (multimedia) WWW refresh pressed 0xE0, 0x21 (multimedia) volume down pressed 0xE0, 0x23 (multimedia) mute pressed
0xE0, 0x27 right GUI pressed
0xE0, 0x28 (multimedia) WWW stop pressed 0xE0, 0x2B (multimedia) calculator pressed
0xE0, 0x2F apps pressed
0xE0, 0x30 (multimedia) WWW forward pressed 0xE0, 0x32 (multimedia) volume up pressed
0xE0, 0x34 (multimedia) play/pause pressed 0xE0, 0x37 (ACPI) power pressed
0xE0, 0x38 (multimedia) WWW back pressed 0xE0, 0x3A (multimedia) WWW home pressed 0xE0, 0x3B (multimedia) stop pressed
0xE0, 0x3F (ACPI) sleep pressed
0xE0, 0x40 (multimedia) my computer pressed
0xE0, 0x48 (multimedia) email pressed 0xE0, 0x4A (keypad) / pressed
0xE0, 0x4D (multimedia) next track pressed
0xE0, 0x50 (multimedia) media select pressed
0xE0, 0x5A (keypad) enter pressed
0xE0, 0x5E (ACPI) wake pressed
0xE0, 0x69 end pressed 0xE0, 0x6B cursor left pressed
0xE0, 0x6C home pressed
0xE0, 0x70 insert pressed 0xE0, 0x71 delete pressed 0xE0, 0x72 cursor down pressed
0xE0, 0x74 cursor right pressed 0xE0, 0x75 cursor up pressed
0xE0, 0x7A page down pressed
0xE0, 0x7D page up pressed
0xF0, 0x01 F9 released 0xF0, 0x03 F5 released
0xF0, 0x04 F3 released 0xF0, 0x05 F1 released 0xF0, 0x06 F2 released 0xF0, 0x07 F12 released
0xF0, 0x09 F10 released 0xF0, 0x0A F8 released 0xF0, 0x0B F6 released
0xF0, 0x0C F4 released 0xF0, 0x0D tab released 0xF0, 0x0E ` (back tick) released
0xF0, 0x11 left alt released 0xF0, 0x12 left shift released
0xF0, 0x14 left control released 0xF0, 0x15 Q released 0xF0, 0x16 1 released
0xF0, 0x1A Z released 0xF0, 0x1B S released
0xF0, 0x1C A released 0xF0, 0x1D W released 0xF0, 0x1E 2 released
0xF0, 0x21 C released 0xF0, 0x22 X released 0xF0, 0x23 D released
0xF0, 0x24 E released 0xF0, 0x25 4 released 0xF0, 0x26 3 released
0xF0, 0x29 space released 0xF0, 0x2A V released 0xF0, 0x2B F released
0xF0, 0x2C T released 0xF0, 0x2D R released 0xF0, 0x2E 5 released
0xF0, 0x31 N released 0xF0, 0x32 B released 0xF0, 0x33 H released
0xF0, 0x34 G released 0xF0, 0x35 Y released 0xF0, 0x36 6 released
0xF0, 0x3A M released 0xF0, 0x3B J released
0xF0, 0x3C U released 0xF0, 0x3D 7 released 0xF0, 0x3E 8 released
0xF0, 0x41 , released 0xF0, 0x42 K released 0xF0, 0x43 I released
0xF0, 0x44 O released 0xF0, 0x45 0 (zero) released 0xF0, 0x46 9 released
0xF0, 0x49 . released 0xF0, 0x4A / released 0xF0, 0x4B L released
0xF0, 0x4C  ; released 0xF0, 0x4D P released 0xF0, 0x4E - released
0xF0, 0x52 ' released
0xF0, 0x54 [ released 0xF0, 0x55 = released
0xF0, 0x58 CapsLock released 0xF0, 0x59 right shift released 0xF0, 0x5A enter released 0xF0, 0x5B ] released
0xF0, 0x5D \ released
0xF0, 0x66 backspace released
0xF0, 0x69 (keypad) 1 released 0xF0, 0x6B (keypad) 4 released
0xF0, 0x6C (keypad) 7 released
0xF0, 0x70 (keypad) 0 released 0xF0, 0x71 (keypad) . released 0xF0, 0x72 (keypad) 2 released 0xF0, 0x73 (keypad) 5 released
0xF0, 0x74 (keypad) 6 released 0xF0, 0x75 (keypad) 8 released 0xF0, 0x76 escape released 0xF0, 0x77 NumberLock released
0xF0, 0x78 F11 released 0xF0, 0x79 (keypad) + released 0xF0, 0x7A (keypad) 3 released 0xF0, 0x7B (keypad) - released
0xF0, 0x7C (keypad) * released 0xF0, 0x7D (keypad) 9 released 0xF0, 0x7E ScrollLock released
0xF0, 0x83 F7 released
0xE0, 0x12, 0xE0, 0x7C print screen pressed
0xE0, 0xF0, 0x10 (multimedia) WWW search released 0xE0, 0xF0, 0x11 right alt released
0xE0, 0xF0, 0x14 right control released 0xE0, 0xF0, 0x15 (multimedia) previous track released
0xE0, 0xF0, 0x18 (multimedia) WWW favourites released
0xE0, 0xF0, 0x1F left GUI released
0xE0, 0xF0, 0x20 (multimedia) WWW refresh released 0xE0, 0xF0, 0x21 (multimedia) volume down released 0xE0, 0xF0, 0x23 (multimedia) mute released
0xE0, 0xF0, 0x27 right GUI released
0xE0, 0xF0, 0x28 (multimedia) WWW stop released 0xE0, 0xF0, 0x2B (multimedia) calculator released
0xE0, 0xF0, 0x2F apps released
0xE0, 0xF0, 0x30 (multimedia) WWW forward released 0xE0, 0xF0, 0x32 (multimedia) volume up released
0xE0, 0xF0, 0x34 (multimedia) play/pause released 0xE0, 0xF0, 0x37 (ACPI) power released
0xE0, 0xF0, 0x38 (multimedia) WWW back released 0xE0, 0xF0, 0x3A (multimedia) WWW home released 0xE0, 0xF0, 0x3B (multimedia) stop released
0xE0, 0xF0, 0x3F (ACPI) sleep released
0xE0, 0xF0, 0x40 (multimedia) my computer released
0xE0, 0xF0, 0x48 (multimedia) email released 0xE0, 0xF0, 0x4A (keypad) / released
0xE0, 0xF0, 0x4D (multimedia) next track released
0xE0, 0xF0, 0x50 (multimedia) media select released
0xE0, 0xF0, 0x5A (keypad) enter released
0xE0, 0xF0, 0x5E (ACPI) wake released
0xE0, 0xF0, 0x69 end released 0xE0, 0xF0, 0x6B cursor left released
0xE0, 0xF0, 0x6C home released
0xE0, 0xF0, 0x70 insert released 0xE0, 0xF0, 0x71 delete released 0xE0, 0xF0, 0x72 cursor down released
0xE0, 0xF0, 0x74 cursor right released 0xE0, 0xF0, 0x75 cursor up released
0xE0, 0xF0, 0x7A page down released
0xE0, 0xF0, 0x7D page up released
0xE0, 0xF0, 0x7C, 0xE0, 0xF0, 0x12 print screen released
0xE1, 0x14, 0x77, 0xE1, 0xF0, 0x14, 0xF0, 0x77 pause pressed

Note: There is no scan code for "pause key released" (it behaves as if it is released as soon as it's pressed)

Scan Code Set 3

The following table shows which scan codes correspond to which keys when using scan code set 3 (for a "US QWERTY" keyboard only):

TODO


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