Difference between instruction sets and processor architecture?

[crazy.wingman]

Can anyone explain me the difference between processor architecture and instruction sets in simplified?

Thanks!!

 

[TuxDave]

Ok. Imagine you had some Ikea furniture you needed to assemble. The instruction set is the language the directions are written in. The architecture is the person reading the directions and building the furniture. So for example, x86 (Intel) instruction set is "English" and you can give it to several English speaking workers (different Intel architectures). Some workers do things smarter than others and can build the furniture faster.

And the depending on the language, maybe it's more wordy to explain what you need to do. Maybe it's faster.

Edit: Actually what I quoted closer to microarchitecture instead of architecture. Maybe someone else can come up with an Ikea furniture analogy.

 

[SecurityTheatre]

Ok. Imagine you had some Ikea furniture you needed to assemble. The instruction set is the language the directions are written in. The architecture is the person reading the directions and building the furniture. So for example, x86 (Intel) instruction set is "English" and you can give it to several English speaking workers (different Intel architectures). Some workers do things smarter than others and can build the furniture faster.

And the depending on the language, maybe it's more wordy to explain what you need to do. Maybe it's faster.

Edit: Actually what I quoted closer to microarchitecture instead of architecture. Maybe someone else can come up with an Ikea furniture analogy.

Yes, you did, but the "architecture" as formally defined is just the combination of the microarchitecture and the instruction set (as a whole).


But in order to be REALLY simple, here is an example.

Instruction Set Architectures: The actual description of valid commands for the CPU. Examples of these are:
x86
Intel-SSE3 (as an extension of x86)
MIPS
ARM
Motorolla 68k

Microarchitecture: The way the chip is built. How many/what kind of ALUs, kind/size of cache, cache associativity, how many/what kind of floating point units, what kind of branch predictor, what kind of other operational units. Examples are:
Intel 80286 (i286)
Intel Netburst (Pentium 4)
Intel Dothan (Pentium M)
AMD Thunderbird (Athlon)
AMD Bulldozer (Athlon XP)
(and hundreds more)


Here is the car analogy.

Instruction set: Gas pedal on the right, brake on the left, shifter in your right hand, turn signal to the left of the wheel, using KPH for the speedo. Uses unleaded.

Architecture: Flat 4 engine, turbocharged with 32-valve dual cam. Bembro brakes and extra stiff swaybar. Pirelli tyres.


Car analogies win.

 

[indy2878]

+12 on the car analogies from this thread! Thanks for the informative analogy explanation of cpu arch. and ISA on this thread to everyone who contributed. Its really useful of a technique for my studies in school.

 

[Dresdenboy]

Car analogies win.

I've often used them. It's fun.

Is there already a site collecting them? I'd call it "CAW" - Car Analogies Wiki.

Car analogies are the new ISA. We could found a school by using CAs to explain everything more advanced.

 

[slugg]

It should be mentioned that there's also a difference between micro architecture and organization.

(micro)architecture: "we have two ALUs"

Organization: "the ALU has a Booth's multiplier."


Back to the car analogies. The instruction set (gas pedal) follows the architecture (flat 4 motor), which has a particular organization (gasoline engine, rather than diesel).

Hope this makes sense...

 

[crazy.wingman]

Thnks Friends!!