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Intel distributes microcode updates as a 2,048 (2 kilobyte) binary blob. [1] The update contains information about which processors it is designed for, so that this can be checked against the result of the CPUID instruction. [1] The structure is a 48-byte header, followed by 2,000 bytes intended to be read directly by the processor to be ...
Below is the full 8086/8088 instruction set of Intel (81 instructions total). [2] These instructions are also available in 32-bit mode, in which they operate on 32-bit registers (eax, ebx, etc.) and values instead of their 16-bit (ax, bx, etc.) counterparts.
Real mode ; 8080 emulation mode (NEC V20/V30 only) Protected mode (Intel 80286) Unreal mode (Intel 80286) Virtual 8086 mode (Intel 80386) System Management Mode (Intel 386SL) Long mode (AMD Athlon 64) x86 virtualization (Intel Pentium 4, AMD Athlon 64) AIS mode (VIA C3 only) First supported platform shown in parentheses
The x86 processors support five modes of operation for x86 code, Real Mode, Protected Mode, Long Mode, Virtual 86 Mode, and System Management Mode, in which some instructions are available and others are not. A 16-bit subset of instructions is available on the 16-bit x86 processors, which are the 8086, 8088, 80186, 80188, and 80286.
The 8086 [3] (also called iAPX 86) [4] is a 16-bit microprocessor chip designed by Intel between early 1976 and June 8, 1978, when it was released. The Intel 8088, released July 1, 1979, [5] is a slightly modified chip with an external 8-bit data bus (allowing the use of cheaper and fewer supporting ICs), [note 1] and is notable as the processor used in the original IBM PC design.
BIOS interrupt calls perform hardware control or I/O functions requested by a program, return system information to the program, or do both. A key element of the purpose of BIOS calls is abstraction - the BIOS calls perform generally defined functions, and the specific details of how those functions are executed on the particular hardware of the system are encapsulated in the BIOS and hidden ...
A control register is a processor register that changes or controls the general behavior of a CPU or other digital device. Common tasks performed by control registers include interrupt control, switching the addressing mode, paging control, and coprocessor control.
The effective 20-bit address space of real mode limits the addressable memory to 2 20 bytes, or 1,048,576 bytes (1 MB). This derived directly from the hardware design of the Intel 8086 (and, subsequently, the closely related 8088), which had exactly 20 address pins. (Both were packaged in 40-pin DIP packages; even with only 20 address lines ...