what do you understand by microprocessor ?
- The microprocessor is simply a programmable integrated device that has computing and decision making capability similar to that of central pricessing unit(CPU).A microprocessor is designed to perform arithmetic and logical operations like addition, substraction,etc.
- Typical microprocessor operations include comparing two numbers and fetching numbers from one area to another. Nowadays,the microprocessor is being used in awide range of products called microprocessor based products or systems.
- A microprocessor typically serves as a central processing unit microprocessor in a computer system.
- The fact that the microprocessor is programmable means it can be instructed to perform given task within its capability.
How Does the Microprocessor Work ?
Assume that a program and data are already entered in the R/W memory(Read/write memory ) The program includes binary instructions to add given data and to display the answer at the seven-segment LEDs .When the microprocessor is given a command to execute the program, it reads and executes one instrucrtion at a time a finally sends the result to the seven-segment LEDs for display.
This process of program execution can best be described by comparing it to the process of assembling a ratio kit. The instructions for assembling the ratio are printed in a sequence on a sheet of paper.One reads the reads the first instruction,then picks up the necessary components of the radio and performs the task.
Evolution of microprocessor.Generation of microprocessors
1st Generation microprocessor (1971-1973):
Intel corporation introduced the first microprocesor,the 4004,in 1971.The 4004 evolved from a development effort while designing a calculator chip set.
After 4004 ,three other microprocessors were introduced Rockwell international PPS-4,Intel 8-bit 8008,and National Semiconductor16-bit IMP-16.
Soon after in the commercial martket the 4004 microprocessor and three other microprocessors were introduced.These three microprocessors are ,the Intel 8-bit 8008,Rockwell international PPS-4 and the National semiconductor 16-bit IMP-16.
The first generation microprocessors system were designed on PMOS(p-type MOS) technology.They were introduced between 1971 to 1973.
2nd Generation microprocessor (1973-1978):
After 1973,second-generation microprocessors such as motorola 6800 and 6809,Intel 8085,and Zilong Z80 evolved.
The second generation microprocessor were designed using NMOS(n-type MOS) technology.
3rd Generation microprocessor (1979-1980):
After 1973,third generation microprocessors such as intel 8086,intel 80186,intel 80286 and motorola 68000/68010 were introduced. These microprocessors include typical processing power and 16-bits wide.
Recently,Intel utilized HMOS technology to fabricate the 8085A.
This processor was eventually discontinued by Intel.
4th Generation microprocessor (1980-1995):
In 1980, the fourh generation microprocessors commercially introduced by intel.The problematic intel 432.these processors are 32 bits wide.Now this processor was eventually discontinued by intel.
Since 1985,more 32-bit microprocessors have been introduced These include Motorola's MC 68020 and 68030 and Intel 80386.
these processors were designed using HCMOS(low-power version of HMOS technology).
Recently,Motorola has inroduced a 32-bit RISC (Reduced instruction set computer) microprocessor with a simplified instruction set called the MC88100.
5th Generation microprocessor (1995 onwards):
These generation processors give high-performance and high-speed that make use of 64-bit processors.
Such processors include Pentium,Celeron,Dual core and Quad core processors
The fifth generation microprocessors represent advancement in specifications.
Types of microprocessor
8085 microprocessor: The 8085 is the most popular CPU amongst all the 8-bit CPUs.The 8085 CPU houses an on-chip clock generator and provides good performance utilizing an optimum set of registors and reasonably powerful ALU.The major limitation of this 8-bit microprocessprs are limited memory addressing capacity,slow speed of execution,limited nuber scratchpad registers and non-availability of compiler instruction set and addresing modes.
8086 microprocessor: The first 16-bit CPU from intel was a result of the designer's efforts to produce more powerful and efficient computing machine.
it has a set of 16-bit general purpose registers, it supports a16-bit ALU,it provides segmented memory addressing scheme.
The major limitation in 8086 was that it did not have the memory management and protection capabilities.
80286 microprocessor:80286 was the first CPU to posses the ability of memory management,privilege and protection.
However,the 80286 CPU had a limitation on the maximum segment size supported by it.
Another limitation of 80286 was that,once it was switched to protected mode, it was difficult to get it back to real mode.The only way of reverting it to the real mode was to reset the system.
80386 microprocessor: 80386 was the first 32-bit CPU from intel.The memory menagement capability of 80386 was enhanced to support virtual memory , paging and four level of protection.
In 80386 the maximum segment size was enhanced and the 80386 could be as large as 4GB.
The 80386 along with its math coprocessors 80387 provided a high speed environment.
80486 microprocessor:The 80486 was designed with an integrated math coprocessor .After getting integrated,the speed of execution of methematical operations enhenced three folds.Also for the first time,an 8 kB four-way set associative code and data cache was introduced in 80486.A five stage instruction pipeline was also inroduced.
Pentium microprocessor: It has a super scaler, super pipelined architecture.It has two integer pipelines U and V , where each one is a 4-stage pipeline.
Pentium has increased the floating point performance due to an on-chip floating point unit.
Pentium-II is the next version of pentium.It incorporates all featurs of Pentium pro and it has alarge cache.
Pentium-III has been developed on 0.25 microtechnology and includes over 9.5 million traansistors.
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