How a CPU Works

[Hardware Secrets Team]

There has been a new article posted.

Title: How a CPU Works
URL: http://www.hardwaresecrets.com/article/209

Here's a snippet:
Even though every microprocessor has its own internal design, all microprocessors share a same basic concept – which we will explain in this tutorial. We will take a look inside a generic CPU architec...

Comments on this article are welcome.

[Skye]

I wonder why they don't make multiple versions of each clockspeed of each processor type, the options being cache sizes. I wouldn't mind having a bit lower clockspeed and a bit higher cache size.

[Gabriel Torres]

Cost:

1. The main problem is that since the cache is huge and usually has more transistors that the CPU core, after being manufactured sometimes the cache is defective but the CPU core is good, and they have to throw out everything. It is a probability issue: the larger the cache the higher the chance of the CPU having manufacting problems (inside the factory, obviously these defective chips aren't sold).

2. Another explanation is regarding the package. Doubling the size of memory cache will double the amoun of physical space required by the cache. If you see a photo of a CPU die you will notice that the memory cache is usually bigger than the CPU core.

3. It also increases the CPU consumption, meaning more heat.

4. It also increases the CPU current leakage, meaning more heat even when the CPU is doing nothing.

For clock is a little bit easier: they don't know up to how many megahertz the CPU will run while they are manufacturing it. Only after the CPU is built and tested the manufacturer learns what is the CPU maximum clock rate. So predicting clock rates inside the factory isn't easy.

Anyway there are many factors to put into consideration and I am sure the manufacturer chooses the most cost-effective one.

Cheers,
Gabriel.

[Skye]

Heh, OK. Thought it was worth a try.

[kabugaw]

Hello. Recently, I've been seeing articles about x86 CPUs and non-x86 CPUs. What are the differences between a x86 CPU and a CPU that's not? Here is the link where someone said that a certain IBM processor runs at 5GHz, but isn't a x86 CPU.

[Gabriel Torres]

Hi,

"x86" means that the CPU is capable of running x86 instructions, i.e. the same kind of instructions that PC software uses. Non-x86 CPUs can't run this kind of instructions and thus you can't run PC software on them. They will need specific software. This kind of CPU isn't for PCs, obviously, but for specific applications.

Cheers,
Gabriel.

[HARDWARE]

Can you explain that external and internal clock thing in different way cuz i didn't understand that clearly.

[Gabriel Torres]

Hello,

All CPUs generate their internal clock signal ("clock" that is referred by the CPU manufacturer like "2 GHz", "1.8 GHz", etc) by multiplying an external clock by a factor. For example, a 2 GHz CPU would generate its 2 GHz internal clock rate multiplying an external 200 MHz clock rate by 10. Notice that this is just an hypotetic example and the actual external clock rate the CPU uses may be different.

Please let us know if you still can't understand and make yourself clear of exactly what you didn't understand.

Cheers,
Gabriel.

[curadebt_fees]

I read the article. It is good and informative for people.