The Microprocessor

.. in the paper there have been common reoccurring phrase such as a microprocessor containing 14 16-bit registers. At this time in the evolution of microprocessors come the 32-bit register, which obviously has double the capacity to hold information for the microprocessor. Because of this simple increase of the register capacity we have a whole different type of microprocessor. Although the 16- bit and 32-bit microprocessors are quite different (meaning they have more compo- nents and such), the 32-bit microprocessors will be described in the same terms as the 16-bit microprocessors were. The remainder of the paper will discuss the 32-bit microprocessor series.

The external data bus is a term that will be referred to in the remainder of the paper is. The data bus is basically what brings data from the memory to the processor and from the processor to the memory (Givone, 123). The data bus is similar to the registers located on the microprocessor but are a little bit slower to access (Givone, 123). The first 32-bit microprocessor in the microprocessor industry that will be dis- cussed is the series 32000 family and was originally built for main-frame computers. In the 32000 family all of the different microprocessors have the same 32-bit internal structure; but may have external bus values such as 8, 16, or 32 bits (Mitchell, 225). In the 32000 family the microprocessors use only 24 of the potential 32 bit addressing space, giving the microprocessor a 16 Mbyte address space (Mitchell, 225).

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The 32- bit registers are set up so there are six 32-bit dedicated registers and then in combina- tion there are two 16-bit dedicated registers (Mitchell, 231). Each dedicated register has its own type of specific information that it holds for processing (Mitchell, 232). The microprocessors oscillator (which now comes from an external source) runs at 2.5 MHz, but due to a divide-by-four prescaler the clock frequency runs at 10MHz. There have been many new ideas put into practice to improve the 32000 series micro- processor generally and thus making it run faster and more efficient. The next family of microprocessor which was fabricated for the microcomputer is the MC68020 32-bit microprocessor which is based on the MC68000 family.

The other microprocessors that are included in this family are the MC68000, MC68008, MC68010 and the MC68012 (Avtar, 302). Before going into the types of components that this microprocessor contains, it should first be know that the making of the MC68020 has been the product of 60 man-years of designing including the manufac- turing of the High-density Complementary Metal Oxide Semiconductor giving the mi- croprocessor high speed and low resistance and heat loss (Avtar, 302). Because of all the work that was put into the MC68020 and its other related microprocessors, it is an extremely complex microprocessor. The MC68020 operates in two modes, these are the user mode(for application programs) or the supervisor mode (the operating system and other special functions) (Mitchell, 155). The user and supervisor modes all have there own specific registers to operate their functions.

The user programming has 17 32-bit address registers, and an 8-bit register (Mitchell, 155). Then the supervisor pro- gramming has three 32-bit, an 8-bit and two 3-bit registers for small miscellaneous functions (Mitchell, 155). All of these registers within the two modes are split up into different groups which would hold different information as usual, but this set up of registers gives the microprocessors a 20 32-bit information storing capacity. The next family of microprocessor is Intels 80386 and 80486 families. The 80386 and 80486 were mostly over all better then the other microprocessors being made by the different companies in the industry at this time, simply because Intel is now the leading microprocessor producer in todays market. The 80386 was a product that evolved from Intels very first microprocessor, the 8-bit 8080 (Mitchell, 85).

Then next came the earlier mentioned 16-bit 8086. The reason why Intel did so well in the market for microprocessors was because every microprocessor that they made was compatible with the previous and future (Mitchell, 85). This means that if a piece of software worked on the 8080 then it worked on the future microprocessors and vice-a- versa. Not only did Intel look forward but they looked back. The main difference between the 80386 and the other 32-bit microprocessors is the added feature of a bar- rel shifter (Mitchell, 88).

The barrel shifter allowed information to switch places mul- tiple times in the registers within a single cycle (Mitchell, 88). The microprocessor contains 8 general purpose 32-bit registers, but with the barrel shifter that is increased to the equivalent of a 64-bit microprocessor. For the most common 20MHz 80386 microprocessor the run time for each cycle is 59 nanoseconds, but for a 33MHz mi- croprocessor the cycle time is reduced to 49 nanoseconds. The next 32-bit microprocessor in market are AT&Ts WE32100 and 32200 (Mitchell, 5). These microprocessors also needed six peripheral chips in order to run, these are termed: Memory Management Units, floating point arithmetic, Maths Accel- eration Units, Direct Memory Access Control, and Dynamic Rand Access Memory Control (Mitchell, 5).

These microprocessors apart from the microprocessors all work an important part of processing the data that comes through the microprocessor. The difference from this microprocessor and the others is because the WE32200 address information over the 32-bit range with the help of a disk to work as a slow form of memory (Mitchell, 9). The WE32200 microprocessor runs at a frequency of 24MHz (Mitchell, 9). The 16-bit and 32-bit microprocessors are a mere page in the great book of processor history. There will be many new and extremely different processors in the near future. A tremendous amount of time and money have been put into the making and improving of the microprocessor.

The improving and investment of billions of dollars are continually going toward the cause of elaborating the microprocessors. The evolution of the microprocessor will continue to evolve for the better until the time when a much faster and more efficient electronic device is invented. This is turn will create a whole new and powerful generation of computers. Hopefully this paper has given the reader some insight into the world of microprocessor and how much work has been put into the manufacturing of the microprocessor over the years. The Evolution of The Microprocessor November 25, 1996 Bibliography Mitchel, H.J.

32-bit Microprocessors. Boston: CRC Press. 1986,1991 Titus, Christopher A. 16-Bit Microprocessors. Indiana: Howard W.

Sams & Co., Inc. 1981 Aumiaux, M. Microprocessor Systems. New York: John Wiley & Sons. 1982 Givone, Donald D.; Rosser, Robert P.

Microprocessors/Microcomputers. New York: McGraw-Hill Book Company. 1980 Avtar, Singh. 16-Bit and 32-Bit Microprocessors: Architecture, Software, and Interfacing Techniques: New Jersey. Englewood Cliffs. 1991 Technology Essays.