This document discusses string primitive instructions in x86 assembly language. It provides an overview of instructions like MOVS, CMPS, SCAS, STOS, and LODS that are used to move, compare, scan, store, and load strings. It also describes how the direction flag affects the increment/decrement of the SI and DI registers. Procedures for comparing, copying, finding the length of, reading, writing, and converting case of strings are also summarized.