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[Off-Topic] [Device Team] [Tech class] Chapter- 15: All about CPU Cores

2017-06-11 09:33:16
19749 213

What is CPU?

CPU (Central Processing Unit) - otherwise known as a processor, is the electronic circuitry within a computer/ mobile devices that carries out the instructions of a computer program by performing the basic arithmetic, logical, control and input/output (I/O) operations specified by the instructions.

What is CPU Core?
The Core of CPU means a physical central processing unit. Each CPU “core” is actually a separate central processing unit, which is the part of the CPU that actually does the work. For example, a dual-core chip may look like a single CPU chip, but it actually has two physical central processing units on the chip and Quad core CPU has 4 central processing unit which makes the processing speed faster.

How does CPU Core work?

The designs of processors are extremely complex and vary widely between companies and even models. Their architectures for every leading company are constantly being improved to pack in the most amount of performance in the least amount of space and energy consumption. But despite all the architectural differences, processors go through 4 main steps whenever they process instructions: Fetch, Decode, Execute, and Writeback.

In the Fetch operation, processor core retrieves instructions that are waiting for it, usually from some sort of memory which includes RAM. Now in modern processor cores, the instructions are usually already waiting for the core inside the processor cache. The processors in the devices have an area called the program counter which essentially acts as a bookmark, letting the processor know where the last instruction ended and the next one begins.

After the fetch operation completes taking the immediate instruction, it goes on to decode it. Instructions often involve multiple areas of the processor core such as arithmetic and the processor core needs to figure this out. Each part has something called an opcode which tells the processor core what should be done with the information that follows it. Once the processor core has figured this all out, the different areas of the core itself can get to work.

At the execute step, the processor knows what it needs to do, and actually goes ahead and does it. What exactly happens here varies greatly depending on which areas of the processor core are being used and what information is put in. As an example, the processor can do arithmetic inside the ALU(Arithmetic Logic Unit). This unit can connect to different inputs and outputs to crunch numbers and get the desired result. The circuitry inside the ALU does all the magic like complex calculation, execution etc.

The final step, called writeback, simply places the result of what’s been worked on back into memory. Where exactly the output goes depends on the needs of the running application, but it often stays in processor registers for quick access as the following instructions often use it. From there, it’ll get taken care of until parts of that output need to be processed once again, which can mean that it goes into the RAM.

The whole process is done in a moment of time which is called  “Instruction Cycle”. These instruction cycles happen ridiculously fast, especially now that we have powerful processors with high frequencies.Remember the above-mentioned process is done only one Core of the CPU. Now if you have Quad Core CPU, then the process will do at 4 CPUs at a time!

This is a very simple description of what is CPU Core and how it works in reality, they are far more complex and do a lot more than we realize. The current trend is that processor manufacturers are trying to make their chips as efficient as possible, and that includes shrinking the transistors. The more CPU cores result in more faster processing output with sufficient amount of RAM.

Credits: Google, Wikipedia, other blogs.
Special Thanks to @ansarifauwaz @paramgagan and fellow DT members

Previous Tech Class Lessons
Chapter 7: Infrared Blaster
Chapter 12: All About Rooting
Chapter 13: All about Kernel

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2017-06-11 09:33:16
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MIUI Beta Tester

Chiyaan Satheesh | from Redmi Note 4


Thanks for sharing
2017-06-11 11:04:44

Pro Bunny

Pinaki3s | from Redmi 3S


Great read!
2017-06-11 11:41:00

Master Bunny

Shreyasrocks97 | from mobile


Thanks for sharing!!!!
2017-06-11 11:48:16

Super Moderator

Naman Mishra | from mobile


Very informative Thread
2017-06-11 11:52:11

Grandmaster Bunny

DEZIRABLE JAVI | from Redmi 3S


wonderful information , thanks for sharing
2017-06-11 11:53:02

Nicely Explained, Keep it up
2017-06-11 12:00:38

Master Bunny

Saichand393 | from Redmi Note 3


nice information.......
2017-06-11 12:29:50

Master Bunny

FF8 | from app


Nice explanation

2017-06-11 12:33:49
Ex, Device team & Spam Hunter Team member

Grandmaster Bunny

Prem | from Redmi Note 4


well explained and useful information thanks
2017-06-11 12:38:06

Rookie Bunny

1661683613 | from Redmi Note 4


ok frnds cooll
2017-06-11 12:50:43
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