Hi viewers it’s been a long time to learn one more electronic device. As one reads the topic title one gets the question that what is a microprocessor? And what is its function and what is the internal structure of the microprocessor. As you all know microprocessor can be called the heart of the microcomputer system. The further information gives u the facts about processors in detail.
As mentioned earlier listening to the word microprocessor the fact or question that comes to one’s mind is what a Microprocessor is, a microprocessor is a chip or a programmable device which accepts the input in the form of binary and processes it according to the instructions stored in the memory, and provides result as output. It is generally termed as the heart of the computer because it performs all operations and controls the system. A microprocessor based system consists of three basic parts namely: microprocessor, the memory, and the peripheral I/O devices and are interconnected by the data bus and address bus and the control bus.
The memory stores the binary instructions and the data for the microprocessors. The memory can be classified into main memory and secondary memory. Microprocessors do not perform the programs stored in secondary memory directly…..
The input/output devices are the means which enables the processor to interact with the physical world. Some of the input devices: keyboard, scanner, A/D converters, switches, cameras, microphones, etc. Some of the output devices are: LEDs, seven-segment displays, LCD displays, printers, and monitors.
Evolution of microprocessors:-
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| Evolution of processors |
- The first microprocessor was introduced in 1971 by the Intel Corporation which was a 4bit microprocessor, Intel 4004. Other 4-bit microprocessors are : Intel 4040, PPS-4(by Rockwell International), T3472(by Toshiba), and so on..
- The first 8-bit microprocessor named Intel 8008 was developed in the year 1972. the first microprocessor using NMOS technology was Intel 8080 developed in 1973. other 8-bit processors are: Intel 8085(in 1975), Zilog’s Z80(1976), and Z800, Motorola’s MC6800(1974) and MC6809, National semiconductor’s NSC800, RCA’s 1802(1976) and so on..
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| Intel 8008 |
- The first multichip 16-bit microprocessor was National semiconductor’s IMP-16, introduced in 1973. the first 16-bit single chip microprocessor was
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| IMP-16 |
- 32-bit processors came into existence in the 1980’s. The world’s first single-chip 32-processor was introduced was introduced by AT & T Bell Labs in the year 1980 which was named as BELMAC-32A. The first 32-bit processor by Intel was iapax 432 (in 1981). Some other 32-bit processors are: Intel 80386(in 1985), Intel 486,Pentium,Pentium pro, Pentium II, PentiumIII, and Pentium IV, AMD’s K5,K6 and K7 and Motorola’s 68020(1985) etc..
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| BELLMAC-32A |
- Some of the popular 64-bit processors: AMD’s AMD64(2003), Intel’s x86-64 chips etc.,.
- Some of the recent processors by Intel are: Intel dual core, Intel core 2 solo, Intel core 2 duo, Intel core 2 Quad, Intel core 2 extreme, Intel core i3, Intel i5 and Intel i7 etc.,. For more details of latest processors of Intel click here
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| Intel i7 |
Inside a microprocessor:
The important functional blocks include ALU, the register file, and the control unit.
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| Internal Architecture |
Arithmetic Logic Unit (ALU):
The ALU is the core component of all processors. It performs entire integer arithmetic and bitwise logical operations of the microprocessor. ALU is a combinational circuit and has two data input lines, a data output line, and a status line. It gets data from registers of the microprocessors, processes the data according to the instructions from control unit, and stores the results in its output registers. All modern ALUs use binary data in 2’s complement format.
The integer arithmetic operations performed by the ALU are addition, subtraction. Some 16-bit, 32-bit and 64-bit microprocessors also performs multiplication and division operations, in other processors multiplication and division operations are performed by writing algorithms using addition and subtraction operations.
Some of the processors performs Logical operations like AND, OR, EXCLUSIVE OR, operations. ALU also performs bit shifting and comparison operations.
Register File: The register file comprises of various registers used primarily to store data, address, and status information during the execution of a program. Some of the commonly found registers in most of processors include: program counter, instruction register, buffer register, status register, the stack pointer, general purpose registers, and temporary registers.
· Program counter: The PC is a register which stores the address of the next instruction to be executed and hence play a central role in the sequence of machine instructions that a processor executes.
· Instruction register: It stores the code of the instruction currently being executed. The control unit extracts the code from the instruction register and processes it.
· Buffer register: Buffer registers interface the microprocessor with its memory system. The two standard buffer registers are: memory address register (MAR) and the memory buffer register (MBR) . the MAR is connected to the address pins of the processor, and the MBR is connected to data pins of the processor. It stores all the data written to and read from the memory.
· Status register: It stores the status outputs of the result of an operation and gives additional information about result of an ALU operation. The status of bits stored in the status register tells about the occurrence or non-occurrence of different conditions...
· Stack pointer: It is a register which is used to store the address of a memory location belonging to the most recent entry in the stack. Processors use stack because it is faster to move data using PUSH and POP instructions than moving data to and from memory using a MOVE instruction.
· General purpose registers: there is a set of registers for general purpose use, designed as general purpose registers. They are used explicitly to store data and address information. With the availability of greater number purpose registers, it would be possible to perform many ALU operations without even a need to store data in external memory..
· Temporary registers: They are used when data have to be stored during the execution of a machine instruction.
Control unit: The control unit governs and co-ordinates the activities of different sections of the processors and I/O devices. It is responsible for controlling the cycle of fetching machine instructions from memory and executing them. It also co-ordinates the activities of input and output devices. It is the most complex of all the function blocks of microprocessor and occupies most of the chip area .
Control units are categorized into two types depending upon the way they are built. These include hard wired and micro coded control units. Hard wired controllers are sequential logic circuits, the states of which respond to the phases of the instruction execution cycle. They are very compact and fast, but are difficult to design. This is also known as RISC design. Micro coded controllers are easy to design; this is also called as CISC designs. These control units offer more flexibility than hard wired control units.
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