Instructures of computer

This is called machine code and it consists of numbers (binary) used to tell the CPU what to do next. They're very simple, such as add or subtract; it can multiply by 2 (called shift); uses only integer numbers; and most of them are used to fetch or store data in memory. The old 8080 had 256 instructions. The Pentium has a few more but most of the are just because it must access a larger memory.