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PROGRAMMING WITH THE ARITHMETIC COPROCESSOR This section of the chapter provides programming examples for the arithmetic coprocessor. Each example is chosen to illustrate a programming technique for the coprocessor. Calculating the Area of a Circle This first programming example illustrates a simple method of addressing the coprocessor stack. First, recall that the equation for calculating […]
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INSTRUCTION SET The arithmetic coprocessor executes over 68 different instructions. Whenever a coprocessor instruction references memory, the microprocessor automatically generates the memory address for the instruction. The coprocessor uses the data bus for data transfers during coprocessor instructions and the microprocessor uses it during normal instructions. Also note that the 80287 uses the Intel-reserved I/O […]
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THE 80X87 ARCHITECTURE The 80X87 is designed to operate concurrently with the microprocessor. Note that the 80486DX–Core2 microprocessors contain their own internal and fully compatible versions of the 80387. With other family members, the coprocessor is an external integrated circuit that parallels most of the connections on the microprocessor. The 80X87 executes 68 different instructions. […]
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THE ARITHMETIC COPROCESSOR, MMX, AND SIMD TECHNOLOGIES INTRODUCTION The Intel family of arithmetic coprocessors includes the 8087, 80287, 80387SX, 80387DX, and the 80487SX for use with the 80486SX microprocessor. The 80486DX–Core2 microprocessors contain their own built-in arithmetic coprocessors. Be aware that some of the cloned 80486 microprocessors (from IBM and Cyrix) did not contain arithmetic […]
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VIDEO DISPLAYS Modern video displays are OEM (original equipment manufacturer) devices that are usually purchased and incorporated into a system. Today, there are many different types of video displays available in either color or monochrome versions. Monochrome versions usually display information using amber, green, or paper-white dis- plays. The paper-white displays were once extremely popular […]
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QUESTIONS AND PROBLEMS 1. Which microprocessor pins are used to request and acknowledge a DMA transfer? 2. Explain what happens whenever a logic 1 is placed on the HOLD input pin. 3. A DMA read transfers data from to . 4. A DMA write transfers data from to . 5. The DMA controller selects the […]
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SUMMARY 1. The HOLD input is used to request a DMA action, and the HLDA output signals that the hold is in effect. When a logic 1 is placed on the HOLD input, the microprocessor (1) stops executing the program; (2) places its address, data, and control bus at their high-impedance state; and (3) signals […]
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DISK MEMORY SYSTEMS Disk memory is used to store long-term data. Many types of disk storage systems are available today and they use magnetic media, except the optical disk memory that stores data on a plastic disk. Optical disk memory is either a CD-ROM (compact disk/read only memory) that is read, but never written, or […]
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SHARED-BUS OPERATION Complex present-day computer systems have so many tasks to perform that some systems are using more than one microprocessor to accomplish the work. This is called a multiprocessing system. We also sometimes call this a distributed system. A system that performs more than one task is called a multitasking system. In systems that […]
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THE 8237 DMA CONTROLLER The 8237 DMA controller supplies the memory and I/O with control signals and memory address information during the DMA transfer. The 8237 is actually a special-purpose micro- processor whose job is high-speed data transfer between memory and the I/O. Figure 13–3 shows the pin-out and block diagram of the 8237 programmable […]
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