The Evaluation of the Microprocessor. The microprocessor has changed a lot over the years, says (Michael W. Davidson, web) Microprocessor technology is progressing so rapidly that even experts in the field are having trouble keeping up with current advances. As more competition develops in this $150 billion a year business, power and speed of the microprocessor is expanding a tan almost explosive rate. The changes have been most evident over the last decade.

The microprocessor has changed the way computers work by making them faster. The microprocessor is often called the brain of the C. P. U. (or the central processing unit) and without the microprocessor the computer is more or less useless. Motorola and Intel have invented most of the microprocessors over the last decade.

Over the years their has been a constant battle over cutting edge technology. In the 80's Motorola won the battle, but now in the 90's it looks as Intel has won the war. The microprocessor 68000 is the original microprocessor (Encarta 95). It was invented by Motorola in the early 80's. The 68000 also had two very distinct qualities like 24-bit physical addressing and a 16-bit data bus. The original Apple Macintosh, released in 1984, had the 8-MHz found at the core of it.

I twas also found in the Macintosh Plus, the original Macintosh SE, the Apple Laser-Writer IISC, and the Hewlett-Packard's Laser Jet printer family. The 68000 was very efficient for its time for example it could address 16 megabytes of memory, that is 16 more times the memory than the Intel 8088 which was found in the IBM PC. Also the 68000 has a linear addressing architecture which was better than the 8088's segmented memory architecture because it made making large applications more straightforward. The 68020 was invented by Motorola in the mid-80's (Encarta 95). The 68020 is about two times as powerful as the 68000.

The 68020 has 32-bit addressing and a 32-bit data bus and is available in various speeds like 16 MHz, 20 MHz, 25 MHz, and 33 MHz. The microprocessor 68020 is found in the original Macintosh II and in the LaserWriter I INT both of which are from Apple. The 68030 microprocessor was invented by Motorola about a year after the 68020 was released (Encarta 95). The 68030 has 32-bit addressing and a 32-bit data bus just like it's previous model, but it has paged memory management built into it, delaying the need for additional chips to provide that function. A 16-MHz version was used in the Macintosh Ii, IIc x, and SE/30. A 25-MHz model was used in the Mac I Ici and the NeXT computer.

The 68030 is produced in various versions like the 20-MHz, 33 MHz, 40-MHz, and 50 MHz. The microprocessor 68040 was invented by Motorola (Encarta 95). The 68040 has a 32-bit addressing and a 32-bit data bus just like the previous two microprocessors. But unlike the two previous microprocessors this one runs at 25 MHz and includes a built-in floating point unit and memory management units which includes 4-KB instruction and data coaches. Which just happens to eliminate the need additional chips to provide these functions.

Also the 68040 is capable of parallel instruction execution by means of multiple independent instruction pipelines, multiple internal buses, and separate caches for both data and instructions. The microprocessor 68881 was invented by Motorola for the use with both microprocessor 68000 and the 68020 (Encarta 95). Math coprocessors, if supported by the application software, would speed up any function that is math-based. The microprocessor 68881 does this by additional set of instructions for high-proforma nce floating point arithmetic, a set of floating-point data registers, and 22 built-inconstant's including p and powers of 10. The microprocessor 68881 conforms to the ANSI/IEEE 754-1985 standard for binary floating-point arithmetic. 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 286 was 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 80386 dx also called the 386 or the 386 dx 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 hasa 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 80386 dx also has a virtual mode, which allows the operating systems to effectively divide the 80386 dx into several 8086 microprocessors each having its own 1-megabyte space, allowing each'8086' to run its own program. The microprocessor 80386 sx also called the 386 sx was invented by Intel in 1988 as a low-cost alternative to the 80386 DX (Encarta 95). The 80386 SX is in essence an 80386 DX processor limited by a 16-bit data bus. The 16-bit design allows 80386 SX systems to be configured from less expensive AT-class parts, ensuring a much lower complete system price. The 80386 SX offers enhanced performance over the 80286 and access to software designed for the 80386 DX.

The 80386 SX also offers 80386 DX comforts such as multitasking and virtual 8086 mode. The microprocessor 80387 SX also called the 387 SX was invented by Intel (Encarta 95). A math, or floating-point, coprocessor from Intel for use with the 80386 SX family of microprocessors. The 387 sx is available in a 16-MHz version only, the 80387 SX, 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 80386 SX instruction set. The 80387 SX also offers perfect operations for sine, cosine, tangent, arc tangent, and logarithm calculations. If used, these additional instructions are carried out by the 80387 SX, freeing the 80386 SX to perform other tasks.

The 80387 SX 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 80387 SX operates individually on the 80386 SX's mode, and it performs as expected regardless of whether the 80386 SX is running in real, protected, or virtual 8086 mode. The microprocessor mi 486 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 hits the teacher's desk or by the time you read this the next super chip will be developed (Encarta 95).