How do you build an archtechture?

[Smartazz]

I was just reading about the G80 architechture. Text
It is truly remarkable, I've never really understood how anybody would go about making an architechture, where do you start, how do people get it done? Thanks.

 

[CTho9305]

Most architectures are evolutions of previous ones. Companies don't usually go from nothing to the Pentium 4 "netburst" architecture in one leap. Even radical redesigns tend to have a lot of small parts in common with previous architectures. Once you have a good understanding of computer architecture (from university classes, experience, etc) a lot of what's in a certain architecture tends to make sense at first glance (or even seem obvious) because there are standard ways of doing a lot of things.

 

[Megamixman]

Lots and Lots of man hours and studying. The building of architecture involves many aspects. Theres the math, the actual logic design, testing of that, real world device, testing of that, optimization, etc. Each of which requires different types of engineers and other brainiacs, of which all have probably done at least a BS, which is a minimum of 4 years of college and probably avg somewhere close to 6-8 years overall. When you get to something like CPU Architecture, you are talking about years of man hours put in by many people.

 

[BrownTown]

Originally posted by: Megamixman
Lots and Lots of man hours and studying. The building of architecture involves many aspects. Theres the math, the actual logic design, testing of that, real world device, testing of that, optimization, etc. Each of which requires different types of engineers and other brainiacs, of which all have probably done at least a BS, which is a minimum of 4 years of college and probably avg somewhere close to 6-8 years overall. When you get to something like CPU Architecture, you are talking about years of man hours put in by many people.

I'd say its ALOT more than just years of manhours, probably at least decades if not centuries when its all said and done. Considering novel architectures take years to develop and probably hundreds of workers. The graphics cards are a little different than CPUs though, each itteration isn't nearly as different as the previous one, and alot of it is just copy paste.

 

[Born2bwire]

The actual layout is generally done usually using VLSI (Very Large Scale Integration). This involves a lot of cell based design because it is impossible to layout by hand an entire chip. Most of the critical or basic circuit elements will be laid out by hand, that is, the physical layout of the silicon doping, metal layers, vias, pins, and etc are set out in a CAD software. From a large library of cells, the larger elements of a circuit are created. For example, if I needed a 32 bit adder for the ALU in my CPU, then I would first design a full 1-bit adder either by hand or by building up from logic gates from a library. Then I can cascade the 1-bit adders to make a 32 bit adder. This involves having some forsight in how I need to arrange the inputs and outputs of the full adder so that you can efficiently daisy chain them. And thus you have an efficient way of making a complex adder. They also need to route the innumerable number of interconnects between pins of different elements of the CPU. Again, the most critical ones are done by hand but most of them are done by computers using algorithms. These algorithms take into account such design aspects as time delays and area on silicon and they use various optimization techniques like simulated annealing to arrange the various circuit elements on silicon and route the various interconnects.

So a lot of the actual design of a CPU now is done by computers due to the immense complexity involved. But the most basic of the layout is generally done by hand and the design is hand tuned accordingly.