INT 10h, INT 10H or INT 16 is shorthand for

BIOS interrupt call BIOS implementations provide interrupts that can be invoked by operating systems and application programs to use the facilities of the firmware on IBM PC compatible computers. Traditionally, BIOS calls are mainly used by DOS programs and some ot ...

10_{hex
Hex usually refers to:

* A curse or supposed real and potentially supernaturally realized malicious wish
* Hexadecimal, a base-16 number system often used in computer nomenclature

Hex, HEX, or The Hex may also refer to:

Magic
* Hex sign, a b ...}, the 17th

interrupt vector An interrupt vector table (IVT) is a data structure that associates a list of interrupt handlers with a list of interrupt requests in a table of interrupt vectors. Each entry of the interrupt vector table, called an interrupt vector, is the addre ...

in an

x86 x86 (also known as 80x86 or the 8086 family) is a family of complex instruction set computer (CISC) instruction set architectures initially developed by Intel, based on the 8086 microprocessor and its 8-bit-external-bus variant, the 8088. Th ...

-based computer system. The

BIOS In computing, BIOS (, ; Basic Input/Output System, also known as the System BIOS, ROM BIOS, BIOS ROM or PC BIOS) is a type of firmware used to provide runtime services for operating systems and programs and to perform hardware initialization d ...

typically sets up a

real mode Real mode, also called real address mode, is an operating mode of all x86-compatible CPUs. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20- bit s ...

interrupt handler In computer systems programming, an interrupt handler, also known as an interrupt service routine (ISR), is a special block of code associated with a specific interrupt condition. Interrupt handlers are initiated by hardware interrupts, software ...

at this vector that provides video services. Such services include setting the video mode, character and string output, and graphics primitives (reading and writing

pixel In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a Raster graphics, raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, p ...

s in graphics mode). To use this call, load AH with the number of the desired subfunction, load other required parameters in other registers, and make the call. INT 10h is fairly slow, so many programs bypass this BIOS routine and access the display hardware directly. Setting the video mode, which is done infrequently, can be accomplished by using the BIOS, while drawing graphics on the screen in a game needs to be done quickly, so direct access to video RAM is more appropriate than making a BIOS call for every pixel. Furthermore, on a modern x86 system, BIOS calls can only be performed in

Real mode Real mode, also called real address mode, is an operating mode of all x86-compatible CPUs. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20- bit s ...

, or

Virtual 8086 mode In the 80386 microprocessor and later, virtual 8086 mode (also called virtual real mode, V86-mode, or VM86) allows the execution of real mode applications that are incapable of running directly in protected mode while the processor is running ...

. v8086 is not an option in

Long mode In the x86-64 computer architecture, long mode is the mode where a 64-bit operating system can access 64-bit instructions and registers. 64-bit programs are run in a sub-mode called 64-bit mode, while 32-bit programs and 16-bit protected mod ...

. This means that a modern operating system, which operates in

Protected mode In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as Memory_segmentation, segmentation, virtual mem ...

(32 bit), or

(64 bit), would need to switch into real mode and back to call the BIOS - a hugely expensive operation. Although most modern systems typically use device drivers that directly set the video mode, it is not feasible for hobbyist systems to have a device driver for every video card - a problem that also plagues older, unsupported systems such as

Windows 98 Windows 98 is a consumer-oriented operating system developed by Microsoft as part of its Windows 9x family of Microsoft Windows operating systems. It was the second operating system in the 9x line, as the successor to Windows 95. It was Software ...

. Such systems instead can drop into Real mode to switch the video mode, then draw to the framebuffer directly. In EFI 1.x systems, the INT 10H and the

VESA BIOS Extensions VESA BIOS Extensions (VBE) is a VESA standard, currently at version 3, that defines the interface that can be used by software to access compliant video boards at high resolutions and bit depths. This is opposed to the "traditional" INT 10h B ...

(VBE) are replaced by the EFI UGA protocol. In widely used

UEFI Unified Extensible Firmware Interface (UEFI, as an acronym) is a Specification (technical standard), specification for the firmware Software architecture, architecture of a computing platform. When a computer booting, is powered on, the UEFI ...

2.x systems, the INT 10H and the VBE are replaced by the

UEFI GOP Unified Extensible Firmware Interface (UEFI, as an acronym) is a specification for the firmware architecture of a computing platform. When a computer is powered on, the UEFI implementation is typically the first that runs, before starting th ...

List of supported functions

''The list is incomplete; use Ralf Brown's list for comprehensive information. Please only add IBM/PC or other common standard functions. 00h through 0fh are CGA.''

References

INT 10h from Ralf Brown's Interrupt List, online version

INT 10h on www.ousob.com
{{DEFAULTSORT:Int 10h BIOS Interrupts

List of supported functions

See also

References