Editing Magnetic-core memory (section)

===Other forms of core memory===
[[File:Ferrite core memory.jpg|thumb|A 10.8&nbsp;× 10.8&nbsp;cm plane of magnetic core memory with 64&nbsp;× 64 bits (4&nbsp;Kb), as used in a [[CDC 6600]]. Inset shows ''word line'' architecture with two wires per bit]]

''Word line'' core memory was often used to provide register memory. Other names for this type are ''linear select'' and ''2-D''. This form of core memory typically wove three wires through each core on the plane, ''word read'', ''word write'', and ''bit sense/write''. To read or clear words, the full current is applied to one or more ''word read'' lines; this clears the selected cores and any that flip induce voltage pulses in their ''bit sense/write'' lines. For read, normally only one ''word read'' line would be selected; but for clear, multiple ''word read'' lines could be selected while the ''bit sense/write'' lines ignored. To write words, the half current is applied to one or more ''word write'' lines, and half current is applied to each ''bit sense/write'' line for a bit to be set. In some designs, the ''word read'' and ''word write'' lines were combined into a single wire, resulting in a memory array with just two wires per bit. For write, multiple ''word write'' lines could be selected. This offered a performance advantage over ''X/Y line coincident-current'' in that multiple words could be cleared or written with the same value in a single cycle. A typical machine's register set usually used only one small plane of this form of core memory. Some very large memories were built with this technology, for example the [[Extended Core Storage]] (ECS) auxiliary memory in the [[CDC 6600]], which was up to 2 million 60-bit words.

====Core rope memory====
{{Main articles|Core rope memory}}
[[Core rope memory]] is a [[read-only memory]] (ROM) form of core memory. In this case, the cores, which had more linear magnetic materials, were simply used as [[transformer]]s; no information was actually stored magnetically within the individual cores. Each bit of the word had one core. Reading the contents of a given memory address generated a pulse of current in a wire corresponding to that address. Each address wire was threaded either through a core to signify a binary [1], or around the outside of that core, to signify a binary [0]. As expected, the cores were much larger physically than those of read-write core memory. This type of memory was exceptionally reliable. An example was the [[Apollo Guidance Computer]] used for the [[NASA]] Moon landings.