2--x86 Processor

There are eight oating point data registers in the

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Unformatted text preview: t The floating-point unit (FPU) performs high-speed floating-point arithmetic. At one time a separate coprocessor chip was required for this. From the Intel486 onward, the FPU has been integrated into the main processor chip. There are eight floating-point data registers in the FPU, named ST(0), ST(1), ST(2), ST(3), ST(4), ST(5), ST(6), and ST(7). The remaining control and pointer registers are shown in Figure 2–7. 2.2.4 Overview of Intel Microprocessors Let’s take a short trip down memory lane, starting when the IBM-PC was first released, when PC’s had 64 KByte of RAM and no hard drives. For More BS-IT Books, Notes & Assignments visit: www.bsit.zxq.net 40 Chapter 2 • x86 Downloaded From: www.bsit.zxq.net Processor Architecture Figure 2–7 Floating-Point Unit Registers. 80-bit Data Registers 48-bit Pointer Registers ST(0) FPU Instruction Pointer ST(1) ST(2) FPU Data Pointer ST(3) ST(4) 16-bit Control Registers ST(5) Tag Register ST(6) Control Register ST(7) Status Register Opcode Register When discussing processor evolution, references to the data bus size are significant because they affect system performance. When a processor uses an 8-bit data bus to transfer a 32-bit integer to memory, for example, the integer must be broken into four parts, and four separate data transfer operations are required to complete the operation. Given that there is a significant delay (called latency) involved in each data transfer operation, an 8-bit data bus transfers data at onefourth the speed of a 32-bit data bus. Intel 8086 The Intel 8086 processor (1978) marked the beginning of the modern Intel architecture family. The primary innovations of the 8086 over earlier processors were that it had 16bit registers and a 16-bit data bus and used a segmented memory model permitting programs to address up to 1 MByte of RAM. Greater access to memory made it possible to write complex business applications. The IBM-PC (1980) contained an Intel 8088 processor, which was identical to the 8086, except it had an 8-bit data bus that mad...
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This note was uploaded on 11/29/2013 for the course CSE 451 taught by Professor Hussein during the Winter '13 term at Fatih Üniversitesi.

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