# phase-change memory > type of non-volatile random-access memory **Wikidata**: [Q1153902](https://www.wikidata.org/wiki/Q1153902) **Wikipedia**: [English](https://en.wikipedia.org/wiki/Phase-change_memory) **Source**: https://4ort.xyz/entity/phase-change-memory ## Summary Phase-change memory is a type of non-volatile random-access memory. This means it retains its stored information even when power is turned off, unlike traditional volatile memory types such as dynamic random-access memory (DRAM) and static random-access memory (SRAM). It is also known by several aliases, including PCM and PRAM. ## Key Facts * Phase-change memory is a type of non-volatile random-access memory. * It retains its information when power is turned off. * This characteristic contrasts with dynamic random-access memory (DRAM) and static random-access memory (SRAM), which only maintain data as long as power is applied. * It is known by aliases such as PCM, PRAM, PCRAM, C-RAM, chalcogenide RAM, ovonic unified memory (OUM), and CRAM. * Phase-change memory is a parent class of 3D XPoint, which is a non-volatile memory technology. * Its Freebase ID is /m/03h2w0, referenced on 2013-10-28. * It has a sitelink count of 19 across various platforms. * The ACM Classification Code (2012) for phase-change memory is 10003453. ## FAQs ### Q: What is phase-change memory? A: Phase-change memory is a type of non-volatile random-access memory. This means it has the ability to retain its stored data even when the power supply is removed, distinguishing it from volatile memory types. ### Q: What are some alternative names for phase-change memory? A: Phase-change memory is known by several aliases, including PCM, PCME, PRAM, PCRAM, C-RAM, chalcogenide RAM, ovonic unified memory (OUM), CRAM, and chalcogenide random-access memory. ### Q: How does phase-change memory differ from DRAM and SRAM? A: Phase-change memory differs from dynamic random-access memory (DRAM) and static random-access memory (SRAM) because it is non-volatile. DRAM and SRAM require continuous power to maintain their data, whereas phase-change memory retains its information even when power is turned off. ### Q: Is phase-change memory related to 3D XPoint? A: Yes, phase-change memory is identified as a parent class of 3D XPoint. 3D XPoint is itself a non-volatile memory technology. ### Q: What does "non-volatile" mean in the context of memory? A: In the context of memory, "non-volatile" means that the memory retains its stored information even when the power supply is removed. This is in contrast to "volatile" memory, which loses its data without continuous power. ## Why It Matters Phase-change memory is significant because it offers a solution to a long-standing challenge in computing: bridging the performance gap between fast, volatile random-access memory (RAM) and slower, non-volatile storage. Traditional RAM, such as DRAM and SRAM, provides high speed but loses all data when power is removed, necessitating slower storage devices like solid-state drives or hard disk drives for persistent data. Phase-change memory, by being both random-access and non-volatile, has the potential to combine the speed of RAM with the data retention of storage. This characteristic could lead to revolutionary changes in computer architecture, enabling instant-on devices, faster boot times, and more energy-efficient systems by eliminating the need to constantly load data from slower storage into volatile RAM. Its ability to retain data without power makes it a crucial technology for future computing paradigms that demand both high performance and data persistence. ## Notable For * Being a type of random-access memory that is inherently non-volatile, meaning it retains data even when power is turned off. * Its fundamental contrast with volatile memory types like dynamic random-access memory (DRAM) and static random-access memory (SRAM), which require continuous power to maintain data. * Serving as a parent class for 3D XPoint, a significant non-volatile memory technology. * Having a wide array of aliases, including PCM, PRAM, and chalcogenide RAM, reflecting its diverse naming conventions. ## Body ### Definition and Core Characteristics Phase-change memory (PCM) is defined as a type of non-volatile random-access memory. Its primary characteristic is its ability to retain stored information even when power is turned off. This feature directly contrasts with volatile memory technologies such as dynamic random-access memory (DRAM) and static random-access memory (SRAM), both of which require continuous power to maintain their data. ### Aliases and Classifications Phase-change memory is known by several alternative names and classifications: * **Aliases:** PCM, PCME, PRAM, PCRAM, C-RAM, chalcogenide RAM, ovonic unified memory (OUM), CRAM, chalcogenide random-access memory. * **Subclass Of:** non-volatile random-access memory. * **Parent Class:** It is a parent class for 3D XPoint, which is also a non-volatile memory technology. ### Identifiers and References Various identifiers and references are associated with phase-change memory: * **Freebase ID:** /m/03h2w0, with a reference publication date of 2013-10-28. * **Sitelink Count:** 19. * **Wikipedia Title:** "Phase-change memory," available in multiple languages including Arabic (ar), Catalan (ca), German (de), English (en), Spanish (es), Estonian (et), Persian (fa), Finnish (fi), French (fr), and Italian (it). * **Wikidata Description:** type of non-volatile random-access memory. * **ACM Classification Code (2012):** 10003453. * **Microsoft Academic ID (discontinued):** 64142963. * **Encyclopedia of China (Third Edition) ID:** 124150. ## References 1. Freebase Data Dumps. 2013 2. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)