What is variable length instruction, What is its importnace in 32 and 64 bit OS

Question

While reading about 32 bit vs 64 bit OS i came to know that there is instruction length varies from 32 bit to 64 bit. What actually it means and what is its importance?

Answer 1

I suppose you are referring to the CPU instruction sets? A 64 bit CPU supports both 32 bit and 64 bit instruction sets. The 64 bit instruction set is more powerful as these instructions can manipulate and calculate with larger data chunks (64 bit instead of 32 bit), can address more memory directly and sometimes can do more using a single instruction. Most 64 bit processors still support the 32 bit instruction set to support older 32 bit software.