In computer science, load-link and store-conditional (LL/SC) are a pair of instructions used in multithreading to achieve synchronization. Load-link returns the current value of a memory location, while a subsequent store-conditional to the same memory location will store a new value only if no updates have occurred to that location since the load-link. Together, this implements a lock-free atomic read-modify-write operation. LL/SC was originally proposed by Jensen, Hagensen, and Broughton for the S-1 AAP multiprocessor at Lawrence Livermore National Laboratory. Load-link is also known as "load-linked", "load and reserve", or "load-locked".