assembly - Where is an ISA stored and how exactly is it taken into account? -

i'm studying makes computer computer

so far understood have

high-level programming language ->

-> compiled low level programming language (assembly language) ->

-> assembler uses send instructions directly cpu using machine code

the instructions must obey corresponding cpu architecture isa (instruction set architecture) cpu uses.

and cpu reads/writes data registry or hdd (or sdd, etc.) through various channels.

the articles i've read far fail mention following 2 (key, pov) aspects of journey instruction makes:

where isa stored? in component of whole system?
and how cpu take account? along journey? "ask" explicitly isa (somehow) if instruction received valid?

a simple description university of virginia :).

an other 1 use full

if need more let me known ;)

ANy