Definition of Microcomputer
Microcomputer is a small computer also called personal computer (PC) which builds with single integrated circuit called Microprocessor as a CPU (Central Processing Unit). The microcomputer system consist of various parts
CPU (microprocessor) which we are going to learn write below
These parts are connected by the parallel lines called buses. See the details about
bus structure of a microcomputer Among the three, the data bus and the control bus are bi-directional and the address bus is a unidirectional bus. The microcomputers are used in everything from smart sewing machines to computer-aided designs systems. Some examples of microcomputers are the Intel 8051 single chip controller, SDK-86: single board computer design kit, the IBM personal computer (PC) and the Apple Macintosh computer etc.
Working of Microcomputer
The microcomputer follows a sequence of instructions - Fetching, Decoding, and Execution. Initially, the instructions are stored in the memory in a sequential order. The microprocessor fetches those instructions from the memory and decodes it for execution. After execution, microprocessor sends the result either to the output port or to store temporary. in the forms of binary code.
Definition of Microprocessor
Microprocessor is a programmable integrated device that has computing and decision making capabilities just like a CPU of computer. A programmable logic device that reads binary instructions from storage device called memory, accepts binary data as input and processes that data accordingly and provides results as outputs. A typical machine is having three components of microprocessors which is heart of microcomputer, memory and input/output devices which shown in figure. These three components interact with each other to perform a given task.
Now a day, the microprocessor is being used in a wide range of products called microprocessor based products or microprocessor - based systems. These products may be simple or sophisticated depending on its applications.
The microprocessor applications are classified in two categories:
Reprogrammable systems : In reprogrammable systems, the microprocessor is used for computing and data processing such as microcomputers or PC. This system having general purpose microprocessor handles large data, mass storage devices (disks) and input/output devices or peripherals.
Embedded systems: In embedded systems, the microprocessor is a part of a final product and we as a user can not modify that program such as washing machines, dish washers, automobile dashboard control, traffic controllers, microwaves etc.
Evolution of Microprocessors
When we see the evolution of microprocessor, generally it categorize with the number of bits that their ALU can work at a time i.e a microprocessor with a 4-bit ALU (can operate 4-bit data at one time) called 4-bit microprocessor.
In 1971, Intel produced 4004, 4-bit microprocessor. It contained 2300 PMOS transistors. The 4004 was a 4-bit device intended to be used with some other devices in making a calculator. Some logic designer saw that the 4004 having the ability to change the function of a system by just changing the programming, rather than redesigning the hardware.
In 1972, Intel came out with the 8008 which was capable of doing a function with 8-bit words. it required 20 or more additional devices to form a functional CPU.
In 1974, Intel announced the 8080, which had a much larger instruction set than the 8008 and only two additional devices required forming a functional CPU. Also 8080 used V-Channel technology MOS transistors, so it operated much faster than the 8008. The 8080 is referred to as a second generation of microprocessor.
After Intel produce the 8080, Motorola came out with the MC6800- 8-bit general purpose CPU and it required only a +5V supply rather than the -5V. for several years the 8080 and the MC-6800 were the top selling 8-bit microprocessors. The trends in processor design had impact of historical development of microprocessors from different manufacturers. Intel started facing competition from Motorola, MOS Technology 6502 used as the CPU in the Apple II microcomputer, and the used in the Radio Shack TRS-80 microcomputer.
To compete, Intel produced the 8085 microprocessor with general purpose CPU which gives most or all of the computing power of earlier minicomputers. To the software engineer, the 8085 was essentially the same as the 8080, an upgrade of the 8080 requiring only a+5V power supply. However, the 8085 had lots of hardware improvements that made it easier to design into a circuit. Motorola then produced the MC6809 which has a few 16-bit instructions, but it still an 8-bit processor.
In 1978 Intel came out with the 8086 which is a full 16-bit processor. There were some 16-bit microprocessors available previously such as National PACE and Texas Instruments 9900 family of devices, but the market wasn’t ready to accept it. Intel 8086 was certainly the highest performance single - chip 16-bit microprocessor when it first introduced. Soon after Intel came out with the 8086, Motorola came out with the 16-bit MC68000. The 8086 and the MC68000 work directly with 16-bit words instead of with 8-bit words. They can address a million or more bytes of memory and execute the instruction much faster than the 8-bit processors.
In 1979, Intel 8088, the first microprocessor to make a real splash in the market was introduced. And the evolution has continued, the PC market moved from the 8088 to the 80286, 80386, and 80486, Pentium, Pentium II, Pentium III, and Pentium 4. Intel makes all of these microprocessors and all of them are improvements of design base of the 8088. The Pentium 4 can execute any piece of code that ran on the original 8088, but it does about 5,000 times faster.
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