Editing Magnetic-core memory (section)

====Combined read and write with modify====
Core memory controllers were designed so that every read was followed immediately by a write (because the read forced all bits to 0, and because the write assumed this had happened). [[Instruction set]]s were designed to take advantage of this.

For example, a value in memory could be read and modified almost as quickly as it could be read and written. In the [[PDP-6]], the <code>AOS*</code> (or <code>SOS*</code>) instructions incremented (or decremented) the value between the read phase and the write phase of a single memory cycle (perhaps signaling the memory controller to pause briefly in the middle of the cycle). This might be twice as fast as the process of obtaining the value with a read-write cycle, incrementing (or decrementing) the value in some processor register, and then writing the new value with another read-write cycle.