ROM, RAM, Flash Memory

Rom

read-only Memory (ROM) is a class of storage medium used in computers and other electronic devices. Data stored in ROM can-only-modified slowly, with difficulty, or not @ all, so it's mainly used to distribute Firmwar E (software that's very closely tied to specific hardware, and unlikely to need frequent updates).

Strictly, read-only memory refers to memory which is hard-wired, such as diode matrix and the later mask ROM. Alth Ough discrete circuits can be altered (in principle), Integrated circuits (ICs) cannot and was useless if the data is bad. The fact that such memory can never was changed is a large drawback; More recently, ROM commonly refers to memory that's read-only in normal operation, while reserving the fact of s ome possible it.

Other types of non-volatile memory such as erasable programmable read Only memory (EPROM) and electrically erasable Progra Mmable read-only Memory (EEPROM or Flash ROM) is sometimes referred to, on an abbreviated, as "Read-only memory" (ROM ); Although these types of memory can is erased and re-programmed multiple times, writing to this memory takes longer and may Require different procedures than reading the memory. ^{[1] when used-less precise, "ROM" indicates a non-volatile memory which serves functions Typicall Y provided by the mask ROM, such as storage of program code and nonvolatile data.}

Ram

random-access Memory(RAM/r æ m /" is a form of computer data storage. A random-access Memory Device Allows data items to is read and written in approximately the same amount of time Regardless of the order in which data items is accessed. ^{[1] in contrast, with other direct-access data storage media such as  Hard Disks, cd-rws, dvd-rws and The Older drum memory, the time required to read and write data items varies significantly depending on their physical locations on the recording medium, due to mechanical limitations such as Media rotation speeds and arm movement delays.}

Today, random-access memory takes the form of integrated circuits. RAM is normally associated with volatile types of memory (such as dram memory modules), where stored I Nformation is lost if power is removed, although many efforts has been made to develop Non-volatile RAM chips.^{[2] other types of non-volatile memory exist that allow random access for read operations , but either does not allow write operations or has limitations on them. These include most types Of rom and a type Of flash memorycalled  nor-flash .}

The both main forms of modern Ram are static RAM (SRAM) and dynamic RAM (DRAM). In SRAM, a bit of data are stored using the state of a six transistor memory cell. This form of RAM was more expensive to produce, but was generally faster and requires less power than DRAM and, in modern co Mputers, is often used as cache memory for the CPU. DRAM stores a bit of data using a transistor and capacitor pair, which together comprise a DRAM memory cell. The capacitor holds a high or low charge (1 or 0, respectively), and the transistor acts as a switch that lets the control Circuitry on the chip read the capacitor's state of charge or change it. As this form of memory was less expensive to produce than static RAM, it was the predominant form of computer memory used in Modern computers.

Flash Memory

Flash memory is a electronic non-volatile computer storage medium that can be electrically erased and reprogrammed. Flash memory is developed from EEPROM (electrically erasable programmable read-only memory). There is both main types of flash memory, which is named after the NAND and NOR logic gates.

Whereas EPROMs had to being completely erased before being rewritten, NAND type Flash memory May is written and read in block s (or pages) which is generally much smaller than the entire device. NOR type Flash allows a single machine word (byte) to being written-?to an erased location-?or read independently.

The NAND type is primarily used in memory CARDS, USB Flash drives, solid-state drives  (those produ CED in or later), and similar products, for general storage and transfer of data. NAND or NOR flash memory is also often used to store configuration data in numerous digital products, a task previously MA De possible by eeprom or battery-powered static RAM. One significant disadvantage of flash memory is the finite number of read/write cycles in a specific block.^{[ citation ]}

Although flash memory is technically a type of EEPROM, the term "EEPROM" was generally used to refer specifically to NON-FL Ash EEPROM which is erasable in small blocks, typically bytes. ^{[citation needed] Because erase cycles is slow, the large block sizes used in flash memory erasing give it a Significant speed advantage-Non-flash EEPROM when writing large amounts of data. As of, flash memory costs much less than byte-programmable EEPROM and have become the dominant memory type wherever a System requires a significant amount of non-volatile, solid-state storage.}

ROM, RAM, Flash Memory