The Evaluation Of The Microprocessor Essay Research — страница 2

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When making the Macintosh II, Apple noticed that when they added a 68881, the improvement in performance of the interface, and thus the apparent performance was changed dramatically. Apple then decided to add it as standard equipment. The microprocessor 80286, also called the 286was invented by Motorola in 1982(Encarta 95). The 286 was included in the IBM PC/AT and compatible computers in 1984. The 286 has a 16-bit resister, transfers information over the data bus 16 bits at a time, and use 24 bits to address memory location. The 286 was able to operate in two modes real (which is compatible with MS-DOS and limits the 8086 and 8088 chips) and protected ( which increases the microprocessor’s functionality). Real mode limits the amount of memory the microprocessor can address to

one megabyte; in protected mode, however the addressing access is increased and is capable of accessing up to 16 megabytes of memory directly. Also, an 286 microprocessor in protected mode protects the operating system from mis-behaved applications that could normally halt (or “crash”) a system with a non-protected microprocessor such as the 80286 in real mode or just the plain old 8088. The microprocessor 80386dx also called the 386 or the 386dx was invented in 1985(Encarta 95). The 386 was used in IBM and compatible microcomputers such as the PS/2 Model 80. The 386 is a full 32-bit microprocessor, meaning that it has a 32-bit resister, it can easily transfer information over its data bus 32 bits at a time, and it can use 32 bits in addressing memory. Like the earlier 80286,

the 386 operates in two modes, again real (which is compatible with MS-DOS and limits the 8086 and 8088 chips) and protected ( which increases the microprocessor’s functionality and protects the operating system from halting because of an inadvertent application error.) Real mode limits the amount of memory the microprocessor can address to one megabyte; in protected mode, however the total amount of memory that the 386 can address directly is 4 gigabytes, that is roughly 4 billion bytes. The 80386dx also has a virtual mode, which allows the operating systems to effectively divide the 80386dx into several 8086 microprocessors each having its own 1-megabyte space, allowing each “8086″ to run its own program. The microprocessor 80386sx also called the 386sx was invented by

Intel in 1988 as a low-cost alternative to the 80386DX(Encarta 95). The 80386SX is in essence an 80386DX processor limited by a 16-bit data bus. The 16-bit design allows 80386SX systems to be configured from less expensive AT-class parts, ensuring a much lower complete system price. The 80386SX offers enhanced performance over the 80286 and access to software designed for the 80386DX. The 80386SX also offers 80386DX comforts such as multitasking and virtual 8086 mode. The microprocessor 80387SX also called the 387SX was invented by Intel(Encarta 95). A math, or floating-point, coprocessor from Intel for use with the 80386SX family of microprocessors. The 387sx is available in a 16-MHz version only, the 80387SX, if supported by the application software, can dramatically improve

system performance by offering arithmetic, trigonometric, exponential, and logarithmic instructions for the application to use-instructions not offered in the 80386SX instruction set. The 80387SX also offers perfect operations for sine, cosine, tangent, arctangent, and logarithm calculations. If used, these additional instructions are carried out by the 80387SX, freeing the 80386SX to perform other tasks. The 80387SX is capable of working with 32- and 64-bit integers, 32-, 64-, and 80-bit floating-point numbers, and 18-digit BCD (binary coded decimal) operands; it coincides to the ANSI/IEEE 754-1985 standard for binary floating-point arithmetic. The 80387SX operates individually on the 80386SX’s mode, and it performs as expected regardless of whether the 80386SX is running in

real, protected, or virtual 8086 mode. The microprocessor mi486 also called the 80486 or the 486 was invented in 1989 by Intel(Encarta 95). Like its 80386 predecessor, the 486 is a full-bit processor with 32-bit registers, 32-bit data bus, and 32-bit addressing. It includes several enhancements, however, including a built-in cache controller, the built-in equivalent of an 80387 floating-point coprocessor, and provisions for multiprocessing. In addition, the 486 uses a “pipeline” execution scheme that breaks instructions into multiple stages, resulting in much higher performance for many common data and integer math operations. In conclusion it is evident by the following that microprocessors are developing at leaps and bounds and it is not surprising that if by the time it