Complex sentence: In contrast an instruction set simulator simulates an instruction set architecture usually faster but not cycle-accurate to a specific implementation of this architecture; they are often used when emulating older hardware, where time precisions are very important from legacy reasons.
Split into simpler sentences: In contrast an instruction set simulator simulates an Instruction Set Architecture usually faster but not cycle-accurate to a specific implementation of this architecture. They are often used when emulating older hardware, where time precisions are very important from legacy reasons.