SoC has application-based memory. These memories are blocks of semiconductor memory used for computing. Semiconductor memory generally refers to a metal oxide semiconductor memory cell manufactured on a single silicon wafer. Memory types include:
Volatile memory: A memory that loses data after power failure. They require a constant power source to store information. Volatile memory is faster and cheaper, which is why it is accepted by the public.
RAM is a volatile memory. The most commonly used RAMs are SRAM and DRAM. SRAM consists of memory cells composed of 1, 3 or 6 transistors. In contrast, DRAM has only one MOSFET and one capacitor that is charged and discharged according to the state of the FET. However, DRAM is easily affected by capacitor leakage current. A significant advantage of DRAM is that it is cheaper than SRAM. If an SoC has a cache hierarchy, SRAM is used for cache and DRAM is used for main memory. This is because the cache requires a faster type of memory compared to main memory.
There are also RAM types designed for non-volatile functions. For example, FRAM and MRAM, which store data in a magnetic state, and PRAM (parameter random access memory), which is used in Macintosh computers to store system settings, including display and time zone settings. There is also RRAM (Resistive Random Access Memory), which has a component called memristor. Memristor is a kind of resistance whose voltage changes with the applied voltage.
Non-volatile memory: The memory of information can be retained even in the absence of power. ROM (Read Only Memory) is a non-volatile memory. Types of ROM include EPROM (Erasable Programmable Read Only Memory), which is a set of floating gate transistors. Ultraviolet erasable programmable read-only memory (UV erasable programmable read-only memory), use ultraviolet light to erase and reprogram data, EEPROM (electrically erasable programmable read-only memory) and flash memory.
The type of memory selected depends on the design specifications and the application.
