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An alternate software system which usually resides in the computer's firmware, or a hardware-assisted debugger, is then executed with high privileges. It was first released with the Intel 386SL . [ 3 ] [ 4 ] While initially special SL versions were required for SMM, Intel incorporated SMM in its mainline 486 and Pentium processors in 1993.
While Intel documents IRQs 0-7 to be mapped to vectors 0x20-0x27, IBM PC and compatibles map them to 0x08-0x0F. IRQs 8-15 are usually mapped to vectors 0x70-0x77. Software interrupt vector numbers are defined by the specific runtime environment, such as the IBM PC BIOS, DOS, or other operating systems.
Such address translations are carried out by the segmentation unit of the CPU. The last segment, FFFFh (65535), begins at linear address FFFF0h (1048560), 16 bytes before the end of the 20 bit address space, and thus, can access, with an offset of up to 65,536 bytes, up to 65,520 (65536−16) bytes past the end of the 20 bit 8088 address space.
In computing, protected mode, also called protected virtual address mode, [1] is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as segmentation, virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software.
The Intel 80286 [4] (also marketed as the iAPX 286 [5] and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non-multiplexed address and data buses and also the first with memory management and wide protection abilities.
The Global Descriptor Table (GDT) is a data structure used by Intel x86-family processors starting with the 80286 in order to define the characteristics of the various memory areas used during program execution, including the base address, the size, and access privileges like executability and writability.
See Intel 64 and IA-32 Architectures Software Developer's Manual. 23: CET: Control-flow Enforcement Technology: If set, enables control-flow enforcement technology. [16]: 2–19 24: PKS: Enable Protection Keys for Supervisor-Mode Pages: If set, each supervisor-mode linear address is associated with a protection key when 4-level or 5-level ...
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.