2--x86 Processor

A risc machine language consists of a relatively

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Unformatted text preview: r marked the beginning of the modern Intel architecture family. The Intel 80386 processor, the first of the IA-32 family, featured 32-bit registers and a 32-bit address bus and external data path. More recent processors, such as the Core 2 Duo, have multiple processor cores. They employ Intel Hyper-Threading technology to execute multiple tasks in parallel on the same processor core. x86 processors are based on the complex instruction set (CISC) approach. The instruction set includes powerful ways to address data and instructions that are relatively high level complex operations. A completely different approach to microprocessor design is the reduced instruction set (RISC). A RISC machine language consists of a relatively small number of short, simple instructions that can be executed quickly by the processor. In real-address mode, only 1 MByte of memory can be addressed, using hexadecimal addresses 00000 to FFFFF. In protected mode, the processor can run multiple programs at the same time. It assigns each process (running program) a total of 4 GByte of virtual memory. In virtual-8086 mode, the processor runs in protected mode and creates a virtual 8086 machine with its own 1-MByte address space that simulates an Intel 8086 computer running in real-address mode. In the flat segmentation model, all segments are mapped to the entire physical address space of the computer. In the multi-segment model, each task is given its own table of segment descriptors, called a local descriptor table (LDT). x86 processors support a feature called paging, which permits a segment to be divided into 4096-byte blocks of memory called pages. Paging permits the total memory used by all programs running at the same time to be much larger than the computer’s actual (physical) memory. The heart of any microcomputer is its motherboard, holding the computer’s CPU, supporting processors, main memory, input-output connectors, power supply connectors, and expansion slots. The PCI (Peripheral Component Interconnect) bus provides a convenient upgrade path for Pentium processors. Most motherboards...
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