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INT 16h, INT 16H or INT 22 is shorthand for BIOS interrupt call 16hex, the 22nd interrupt vector in an x86-based computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides keyboard services. This interruption is responsible for control of the PC keyboard.


This interruption is responsible for obtaining basic keyboard functionality, i.e. is responsible for collecting the keystrokes, obtain the status of the buffer of keyboard, etc. The standard encoding of the keyboard that offers the INT 16 h is a US keyboard. To adapt the coding of the INT 16h to another type of keyboard (for example, an international keyboard), the code must analyze the scan-code of the key pressed, and then perform suitable interpreting.

For keyboards with 101 letters or more, there are some keys that INT 16h interprets as expanded keys, which have a scan-code that is different from normal keys (e.g., key pause).

List of services of the INT 16 h[edit]

Function Function code(AH) Device
Read key press 00h Keyboard
Get the State of the keyboard buffer 01h Keyboard
Get the State of the keyboard 02h Keyboard
Establish repetition factor 03h Keyboard
Simulate a keystroke 05h Keyboard
Get the ID of the keyboard 0Ah Keyboard
Read expanded keyboard character 10h Expanded keyboard
Obtain status of the expanded keyboard buffer 11h Expanded keyboard
Get expanded keyboard status 12h Expanded keyboard

INT 16h AH=00h - read keystroke[edit]

Function Function code(AH) Device Return
Read key press 00h Keyboard AH[1] = Scan code of the key pressed down AL = ASCII character of the button pressed

See also[edit]


  1. ^ "Scan codes".

External links[edit]