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The “Central Processing Unit”, more generally referred to as ‘processor‘ is the brain of the computer. The human brain handles all human activities, taking in input from various organs like the eyes, ears, and tongue, interpreting it and then providing necessary output to the organs. The nerves and spinal cord help in transferring the signals to and fro. Similarly, the processor takes in input, processes it and generates output accordingly. It has a set of registers or temporary storage spaces and buses for assisting it with the processing. However, there is a vast difference between the human brain and a processor. The former is far more complex in the way it has been designed and the way it functions. We shall however, stick to the details of a computer processor in this piece.
Basic Operation Explained:-
The processor is essentially an electronic circuit that executes a program or a set of instructions that are fed to it. The program is stored in the RAM or program memory of the computer. Each instruction of the program is retrieved from the memory, fed to the processor, which understands what needs to be done, performs the necessary task and then provides an appropriate output. Thus, one cycle of the processor’s operation consists of 4 steps – fetch, decode, execute and output.
Fetch – Retrieval of instruction from memory.
Decode – Breaking down of the instruction to understand or interpret what needs to be done.
Execute – Performing of the operation.
Output – Sending the result of the operation either back to the memory or storing in some temporary location for later use.
There is a program counter which points to the memory location of the instruction being processed. Once a particular instruction is processed, it is incremented to point to the next instruction.
Processor speed (Clock speed) – When you hear terms like MHz and GHz, they mean the number of cycles the processor can execute in one second. Each cycle would consist of fetch, decode, execute and output.
So 1 MHz means – 1,000,000 cycles in one second
1 GHz means – 1,000,000,000 cycles per second
Cache – This is another commonly seen term in the specs of processors. Cache is a temporary storage space, where instructions and results are stored temporarily. Generally, instructions are retrieved from the main memory or RAM, and are sent to the processor through the front side bus, for execution. However, sometimes the speed at which the CPU executes an instruction is much faster than the speed of retrieval of instruction from the main memory. This is when the processor stalls. In order to overcome this issue, a set of instructions are temporarily stored, prior to execution, in the cache, from where their retrieval is much faster.
Bit rate – Terms like 32-bit and 64-bit refer to the size of the word that can be moved from the memory to the processor during a single go. This generally refers to the size of the front bus, that carries data between the storage and the processor, or the size of a single memory unit. A 32-bit machine, can transfer 32 bits of data, at a time from the memory to the processor.
Microprocessors – Initially, the term CPU was broadly used for referring to the computers of olden days. They were huge and were designed to perform a specific task only. For example, there were CPUs made just for addition of numbers. Then came processors which could handle more than a single kind of task. However, they had to be re-wired every time for handling the different tasks. Processors went through a galaxy of changes with the advent of newer technologies. Their size shrunk with each new technology. Finally, when the era of integrated chips came, processors with packages of the size of a small postal stamp were manufactured. The dramatic reduction in size led to naming these processors as microprocessors.
Dual Core Processors – Sometimes a single processor might not be able to meet the needs of high speed multi-processing. Generally when there are many processes running simultaneously on a machine, each task is attended to turn by turn. This is called multi-tasking. This gives a feel that all processes are happening in parallel. A single processor handling all the retrieval and processing of data, can slow down speed and step down performance as well. In such a scenario, if there are 2 processors handling the tasks, the speed of operation can be considerably increased. Like they say – “Many hands make less work.” Thus comes the concept of dual core. A dual core processor is equivalent to having 2 processors in one. They might have separate caches, while they share the other resources and the load too. Recent developments have led to the making of quad core processors too. There is news that Intel is working on 80-core processors also!
Currently many of the laptops ship with Intel processors. Some of them employ AMD processors as well. However, Intel remains the undisputed king in the kingdom of processors. Intel’s processors started with the 8080 and went on with 8088, 80286, 80386 and 80486. These processors were replaced by the more efficient Pentium series. These Pentium processors were employed in desktop computers as well as in mobile computers (laptops). Then came the Intel Atom processors which featured a completely new design and consumed much less power than the previous processors. Most of the laptops, notebooks and netbooks of today, incorporate the Intel Atom processors.
The processor technology graph is currently a steep rising one. Will future processors equal the human brain? Will this actually be a threat or a boon to man? Everything is a haze right now.
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