Editing System on a chip (section)

==== Memory ====
{{Further|Computer memory}}
SoCs must have [[semiconductor memory]] blocks to perform their computation, as do [[microcontroller]]s and other [[embedded system]]s. Depending on the application, SoC memory may form a [[memory hierarchy]] and [[cache hierarchy]]. In the mobile computing market, this is common, but in many [[Low-power electronics|low-power]] embedded microcontrollers, this is not necessary. Memory technologies for SoCs include [[read-only memory]] (ROM), [[random-access memory]] (RAM), Electrically Erasable Programmable ROM ([[EEPROM]]) and [[flash memory]].<ref name="Furber ARM" /> As in other computer systems, RAM can be subdivided into relatively faster but more expensive [[Static random-access memory|static RAM]] (SRAM) and the slower but cheaper [[Dynamic random-access memory|dynamic RAM]] (DRAM). When an SoC has a [[Cache (computing)|cache]] hierarchy, SRAM will usually be used to implement [[processor register]]s and cores' [[CPU cache|built-in cache]]s whereas DRAM will be used for [[main memory]]. "Main memory" may be specific to a single processor (which can be [[Multi-core processor|multi-core]]) when the SoC [[Multi-processor system-on-chip|has multiple processors]], in this case it is [[distributed memory]] and must be sent via {{Section link||Intermodule communication|nopage=y}} on-chip to be accessed by a different processor.<ref name=":1" /> For further discussion of multi-processing memory issues, see [[cache coherence]] and [[memory latency]].