CPU & Mobo Creation

[guy93]

I have always wondered, can somebody help me, on how motherboards and CPU's are actually made. Like, its a piece of metal and plastic and stuff. How do they even program them to do something, for example, the motherboard with the BIOS. How does the CPU know what to do? How do people make such things?

 

[Billb2]

You ask a question that requires a very, very complex answer that would fill an encyclopedia.

In the most simple explaination:
There are two kinds of electrical "signals" in a motherboard and CPU. Analogue and digital.
An analogue signal is electrity flowing down a wire. If you hook a motor to the wire it spins. If you hook a light to the wire it lights. This type of signal spins the disk in a CD/DVD or hard drive, drives the motors in the fans, etc.
With digital signals the electricity in the wire is on for a while and then off for a while (and those are very short whiles!). If you hook a transistor to the wire the transistor will do one thing if the electricity is on and a different thing if the electricity is off. Transistors are basically what is in CPUs and integrated circuits, millions of then in a CPU. By designing circuits containing a lot of transistors to react to different combinations of offs and ons a lot for possibilities can happen. For example, a signal is sent from the hard drive to the CPU and then to the video card and the to the monitor. The signal from the HDD is a series of ons and offs. When that particular series (say on, on, off off, on, on on, off) gets to the CPU (through the HDD cable and the circuits on the motherboard) it causes the first transistoe in the CPU to react in a certain way, which causes the second transistor to act in a certain way and so on until finally the last transistor sends it's signal to the Video card. The same kind of thing happens in the video card and the signal is finally sent to the monitor, where the transistors send a signal to the screen that changes one pixel on the screen from dark red to light red.

Note that I used an example of a digital signal with eigtht choices of on and off. With an 8 bit signal there are 2x2x2x2x2x2x2x2=65536 possible combinations of on/off, so a 8 bit signal can "say" 65536 different "words" to a transistor. In the exanple I gave the single 8 bit "word" said to turn one pixel from dark red to light red!) Modern computers use 64 bit words so there are millions of different "words" that can pass between transistors.

Again, this is a very simplistic explaination, but I hope it helps you to understand how a motherboard, it's peripherals and the CPU communicate with each other.

 

[slugg]

Originally posted by: Billb2
You ask a question that requires a very, very complex answer that would fill an encyclopedia.

In the most simple explaination:
There are two kinds of electrical "signals" in a motherboard and CPU. Analogue and digital.
An analogue signal is electrity flowing down a wire. If you hook a motor to the wire it spins. If you hook a light to the wire it lights. This type of signal spins the disk in a CD/DVD or hard drive, drives the motors in the fans, etc.
With digital signals the electricity in the wire is on for a while and then off for a while (and those are very short whiles!). If you hook a transistor to the wire the transistor will do one thing if the electricity is on and a different thing if the electricity is off. Transistors are basically what is in CPUs and integrated circuits, millions of then in a CPU. By designing circuits containing a lot of transistors to react to different combinations of offs and ons a lot for possibilities can happen. For example, a signal is sent from the hard drive to the CPU and then to the video card and the to the monitor. The signal from the HDD is a series of ons and offs. When that particular series (say on, on, off off, on, on on, off) gets to the CPU (through the HDD cable and the circuits on the motherboard) it causes the first transistoe in the CPU to react in a certain way, which causes the second transistor to act in a certain way and so on until finally the last transistor sends it's signal to the Video card. The same kind of thing happens in the video card and the signal is finally sent to the monitor, where the transistors send a signal to the screen that changes one pixel on the screen from dark red to light red.

Note that I used an example of a digital signal with eigtht choices of on and off. With an 8 bit signal there are 2x2x2x2x2x2x2x2=65536 possible combinations of on/off, so a 8 bit signal can "say" 65536 different "words" to a transistor. In the exanple I gave the single 8 bit "word" said to turn one pixel from dark red to light red!) Modern computers use 64 bit words so there are millions of different "words" that can pass between transistors.

Again, this is a very simplistic explaination, but I hope it helps you to understand how a motherboard, it's peripherals and the CPU communicate with each other.

Sure, why not. But let's go ahead and assume that 2^8 is 256 instead... and that 8 bits is a byte, and that words vary from 1 to 8 bytes depending on the cpu

 

[Billb2]

Originally posted by: Billb2
2x2x2x2x2x2x2x2=65536

Originally posted by: slugg
Sure, why not. But let's go ahead and assume that 2^8 is 256 instead... and that 8 bits is a byte, and that words vary from 1 to 8 bytes depending on the cpu

I knew that!

 

[esun]

Board level design is mostly interfacing various components.

If you were to pick up a chip (say a memory), you'd have some specification that said it needed to be connected in a certain way. It needs some pins to provide power, which must be a certain amount and with so much variation, so you have some circuitry around it that provides power. It must interface with the northbridge so you run the I/O pins there. The physical components you see on the motherboard are connected by thin strips of copper called traces. Basically, you make a pattern on the board out of copper by applying various chemicals to the board. Then you solder in the devices you want to connect in the appropriate locations.

As for the CPU (and all chips on the board), they are made via lithography. Basically you take a wafer of silicon and etch away little pieces of it. The basic way photolithography works is you put down a layer of some material, then shine light on some portions of that material to change the properties of the material (a mask is used to define where the light penetrates), then etch away the portions that were exposed to light. This allows you to construct layers of materials that eventually become transistors, resistors, capacitors, etc.

Regarding how a CPU actually works, it's basically designed to take instructions and execute them. An instruction is just a binary string, some number of 1's and 0's. Some portion of that string defines a command. Some of it defines data. For example, it might be an add instruction. So you provide it two numbers and a destination register, and it'll add those numbers and put it in the appropriate register. With these primitive commands you can produce any behavior you want.

Anyway, that's a very basic look at everything. You'll need a class on computer architecture to get a good idea of how things work at a logical level. You'll need many, many classes in circuits/devices to get a good idea of how things work at a physical level.

 

[mutz]

Basically, you make a pattern on the board out of copper

copper?
isn't it, tin?!

that's a very basic look

i'd say if might, extremely widely general.
it seems this guy expected some easy view at it,:laugh:
look, if u'r sirious at understanding how a CPU exactly works, i'd start with a CPU, and leave the MB aside,
u'll have to dig very deeply, into photolithography, the electromagnetic spectrum (in order to understand something about frequencies),
dig into reverse engineering, the operation of memory through software,bits&bytes,words etc.,the whole binary system, understanding what means 32bit&64bit buses&lines and so on,
understanding assembly, CPU architecture&instruction set, understand what is an ALU&generaly how it operates and designed, the operation of adders,shifters and ofcourse and maybe above all,
logic gates.
after u get all that, u'd better study some chemistry in order to understand the benefits of semiconductor material, they're palce in the periodic table, some sub atomic processes as differences between n type&p type, processes inside transsistor, generally about transsistors,
understanding they're operation, the operation of memory through hardware, the structure of memory cells, how memory phisically operates,almost everything about registers (from SW&HW aspect),conceptualy FPU, temperatures, technologies implemented inside CPU's such as pipelining, multithreading, basic design of bioses and SPI chips and so on.
only then u'll be able to understand some more complex things.
realy, asking such question, is like trying to understand an atom bomb, without any background in physics.
after u understand +-everything, good,
come ask this question again, and there would be purpose in answering it.
i would've refer u to some info, but, it seems u havn't made any effort to look for it u'rself, u'r question is too general,
maybe start with wiki..
the beggining might be there.:sun:

 

[Eureka]

It's copper, not tin. Tin is used for solder, but actual traces are copper. I intern as a board designer and my job is actually doing the PCB layouts. Its insane how much work goes into routing those little lines.

You probably want to take a basics design class to get into the theory. The heart of electronics are in logic gates, and I believe the industry standard is to use NAND gates. These are built using diodes and transistors, the exact method I can't tell you. But what these gates do is when you put in a voltage towards one end, it gives you a voltage on the other end. And this is how logic 1 and logic 0 works. Voltage in the upper half is considered to be a logic 1, voltage in the lower half of the range is a logic 0. So for an AND gate, it "multiplies" that 1 and 0, so if you have an input of 1 and 0, then your output is 0. If you have an input of 1 and 1, then your output is 1. The NAND gate effectively does the same thing, except it inverts the output. So that when you have a 1 and 1, the output is 0, and the rest outputs 1.

When you have enough NAND gates, you can build more complex functions. However this only limits you to combinational logic. Then you have sequential circuits, in which one of the inputs is linked to the output, allowing the effective use of 'states'.

 

[Modelworks]

A really good read on how a cpu works from the very basics. This guy built a cpu then a complete computer using only logic gates and wire wrapping. Quite a feat. Not sure I would have the patience to wire wrap all those connections.
http://www.homebrewcpu.com/

 

[mutz]

So for an AND gate, it "multiplies" that 1 and 0, so if you have an input of 1 and 0, then your output is 0. If you have an input of 1 and 1, then your output is 1.

a good explanation.
the real meaning of logic gates seems to be hard to comprehend (not from the hardware aspect) but rather from the logic behind it..

A really good read on how a cpu works from the very basics. This guy built a cpu then a complete computer using only logic gates and wire wrapping. Quite a feat. Not sure I would have the patience to wire wrap all those connections.
http://www.homebrewcpu.com/

thats a crazy machine, couldn't believe someone would be able to create such thing at home..:laugh:

It's copper, not tin. Tin is used for solder, but actual traces are copper. I intern as a board designer and my job is actually doing the PCB layouts. Its insane how much work goes into routing those little lines.

but u do see sometimes PCB's made out of silveric mater..
anyway, while looking at a standart MB, it indeed, realy seems like a very hard thing to design&create..

 

[esun]

Originally posted by: Eureka
It's copper, not tin. Tin is used for solder, but actual traces are copper. I intern as a board designer and my job is actually doing the PCB layouts. Its insane how much work goes into routing those little lines.

You probably want to take a basics design class to get into the theory. The heart of electronics are in logic gates, and I believe the industry standard is to use NAND gates. These are built using diodes and transistors, the exact method I can't tell you. But what these gates do is when you put in a voltage towards one end, it gives you a voltage on the other end. And this is how logic 1 and logic 0 works. Voltage in the upper half is considered to be a logic 1, voltage in the lower half of the range is a logic 0. So for an AND gate, it "multiplies" that 1 and 0, so if you have an input of 1 and 0, then your output is 0. If you have an input of 1 and 1, then your output is 1. The NAND gate effectively does the same thing, except it inverts the output. So that when you have a 1 and 1, the output is 0, and the rest outputs 1.

When you have enough NAND gates, you can build more complex functions. However this only limits you to combinational logic. Then you have sequential circuits, in which one of the inputs is linked to the output, allowing the effective use of 'states'.

Just to clarify, diodes are very rarely used in logic (making "good" diodes in a CMOS process can be difficult, though they'd typically be available in a BiCMOS process, but those are more expensive than pure CMOS, which dominates the market today).

Also, it's not exactly that people use just NAND gates. Static CMOS logic is an inverting logic family. What that means is that due to how the gates are designed, when the inputs go 0 --> 1, the outputs go 1 --> 0. That means when given the option of using NAND/NOR/NOT or using AND/OR/NOT, designers will use NAND/NOR/NOT since otherwise they'd just have extra inverters along the chain (though this is not always the case, since sometimes we want extra gates for speed reasons).

But there are many other logic families out there aside from static CMOS, including domino logic, current-mode logic, differential logic, etc. The vast majority of logic is static CMOS (since it's so easy to design), but these other families are used in specialized circumstances.

 

[Modelworks]

Originally posted by: mutz
[
but u do see sometimes PCB's made out of silveric mater..
anyway, while looking at a standart MB, it indeed, realy seems like a very hard thing to design&create..

Those are not made of silver. In a lot of lower cost pcb manufacturing they apply a thin coat of tin to the copper to make it easier to solder and because bare copper begins to age quickly. It is easy to do, just have a really clean board and you immerse it in a liquid that contains a tinning solution. The board almost instantly turns silver looking.

A good overview on the basics
http://www.riccibitti.com/pcb/pcb.htm


I prefer to use muriatic acid + hydrogen peroxide as an etchant since it can all be bought at local stores and it works faster.


This is the stuff used to make tin plating solution.
http://www.parts-express.com/p...cfm?Partnumber=340-188

 

[RedArmy]

I could take you through the process of how the physical portion of a PCB is made since I worked at EIT where that's all I did each day (However, I think I'm too lazy to do that). In short, it's a pretty cool process at some points, but other areas are just mind-numbingly boring.