How does a CPU work?

[TruculentTucan]

Could someone explain this to me. I don't get it all. There is the cermanic tile, the core, and the pins, but what the hell do they do?

 

[Zepper]

I doubt that anyone is going to take the time to fully explain this here--way too lengthy. There is a heavily illustrated book called "How Computers Work". Go to your local bookstore and read the section on CPU for a fairly good answer. Other references can provide deep detail, if you're interested.
Simply put: Ceramic or plastic is foundation for core, pins and connection traces between them--holds them in proper alignment and provides some radiation surface for cooling.
. Pins carry all signals between mobo and cpu. Some pins carry power, some are grounded, some carry data to/from cache, registers and RAM, some carry control signals like IRQ (Interrupt ReQuest).
. Core stores (temporarily) and processes data and program instructions (really just a specialized form of data) based on signals from control pins and instructions from programs.
.bh.

 

[Wingznut]

I guess there's a couple directions to go, to answer that question. Are you asking how the cpu's are built, how the transistors and circuits work, or how the instructions work?

Sohcan wrote an excellent post on how instructions work in this thread.

 

[Sohcan]

Thanks Wingz

All CPUs (that I know of) use the stored-program concept of computing...the memory stores instructions and data, and the CPU fetches the instructions, executes them, and stores the results back into memory.

There are three main classes of instructions (from a RISC model perspective):
- Arithmetic/Logical: performs arithmetic (add, subtract, multiply, etc) and logical (AND, OR, NOT, etc) operations on operands. The instructions are executed by the Arithmetic/Logical Unit (ALU), and typically use registers as temporary storage for the operands.
- Load/Store: fetches or stores data from the memory into the register file.
- Branch/Jump: Conditionally/Unconditionally changes the flow of instruction execution. Normally the CPU executes instructions serially (ie, instruction at address X, then X+1, then X+2, etc). A branch instruction might dictate that if register X is less than 0, branch to instruction at address Y.

For a bit more detailed architectural and logical explanation, check out my last two posts in the thread Wingz linked.

 

[BurntKooshie]

Sochan, I have the feeling that, at somepoint, you'll either write a book about computer architecture with someone you've met online, or just venture off and write one yourself.

 

[CTho9305]

what BK said. based on posts here, i'd say, it'd be with bk too

 

[Wingznut]

I've always had a feeling that Sohcan will end up teaching (in the industry) what he knows.

 

[Sohcan]

Aw, shucks guys



<< I have the feeling that, at somepoint, you'll either write a book about computer architecture with someone you've met online, or just venture off and write one yourself. >>

Hehe, but why improve on Patterson and Hennessey's perfection?