Principle of a CPU

[5614]

Yep... and just to make it clear those are standard symbols.

 

So a NOT gate is always shown using the triangle with a circle on the point. So you just get used to what means what.

 

As for the AND vs NAND, well a NAND gate is the same as an AND gate but it also has a circle on the end of it. In your picture you only have AND gates (and the one on the right is an OR gate).

 

NAND gates: http://www.faqs.org/docs/electric/Digital/04106.png

[Nacelunk]

All right, the diagram is pretty straightforward - Q=0 is it?

[bascule]

Somebody on these forums said it was about 30% faster. But only if you have programs that utilize the extra functionality. On Windows a 64bit processor will preform no faster than a 32 bit one and will suck just as much as it normally does.

 

That would be me. AMD64 gets a 30% average speed boost from having 8 general purpose registers instead of the 4 provided by IA32

[Ophiolite]

although I did have to build the basic Gates in transistors during early educational years and also did the same with Relays just for the fun of it

I recall building a transistor based 'calculator' that added two binary numbers together. The numbers were input by setting switches for each bit, and the result was displayed by a series of lights. I called it BASIL (Binary Adder Subtractor with Indicator Lights).

Knowing how that worked helped a decade later when I found it useful to write assembly language diagnostics for HP2100 mini computer systems. Happy days, when 4k of RAM was unbelievably large (and impossibly expensive).

[YT2095]

actualy the last computer I built only had 4k also, then I Upgraded it to 8K

 

take a look at the links in the 1`st post: http://www.scienceforums.net/forums/showthread.php?t=2893

I even had to build my own EPROM programer from scratch too, I couldn`t afford to buy one at the time.

it`s 15 years old now and still working!

[sabbath]

an example of 16 bit buses i think were the old pcs run on windows os such as 98 and down.

the new ones such as pentium 4 run on 32 bit buses...

 

and as to the cpu...to understand how it works one must study both the hardware (physical) and software (program, etc) aspects of the cpu.

 

in a physical standing the cpu is nothing but highly miniaturized logic circuits mounted on an IC specifically Very Large Scale ICs. It's nothing but electronic circuits, that serve as pathways and relay stations were electronic pulses flow.

 

but with the BIOS, the CMOS, the RAM, ROM and the POST and the OS this piece of metal comes to life and processes data into information.

 

How the CPU works is through the integration of software and hardware.

[5614]

All right, the diagram is pretty straightforward - Q=0 is it?

Well it depends on what the inputs are.

 

If A and B are 1 (ie. they are on) then Q = 0 because the for the AND gates one input is on, one is off, so the output of the AND gates are 0. The input for the OR gate is 0 and 0, so the output of the OR gate is also 0.

[YT2095]

actualy the whole thing`s a waste of 2 good NOT gates, 2 good AND gate`s and OR gate, off the top of my head looking at it, you may as well have just used a single XOR gate and be done with!

[gcol]

EXOR, yes, but I recognise that diagram from one of the sites I referenced, and the point of it was to show that an EXOR was an example of an "artificial" logical unit composed of simpler basic units.

[5614]

EXOR??? It is XOR.

 

There are several examples of logic gates which can be made up using other logic gates, this is one and was (seemingly) meant to be, but YT didn't know so well spotted, give that man a beer!

[gcol]

XOR. correct. EXOR was a throwback to when we had to make extremely complex boolean functions by joining many basic functions together. To avoid confusion, we usually referred to it by its full name, EXclusive OR, hence the E.

[5614]

What would you get XOR confused with? OR? Did you use NOT-AND instead of NAND or something? Excuse my ignorance, just interested!

[1veedo]

Is it just me or does it seem this entier thread has been about software and not the actual, physical reasons a processor works?

 

You learn about and/or/whatever gates in computer science class. We had to write programs with them -- make flow charts like the one above.

[Nacelunk]

computer science class

What's the computer science class? Is it in school or in college?

[YT2095]

Gcol, EXOR pronounced is right, but writen it`s just XOR, exclusive OR is the function.

basicly it differs in the truth table by not allowing 1 and 1 as valid inputs, it`s Exclusively A or B and not both.

an ordinary OR will accept A and B as a valid input.