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This article mainly introduces what are the characteristics of ROM and RAM, which are very detailed and have certain reference value. Friends who are interested must finish reading them.

Rom refers to read-only memory, which works in a non-destructive read-out mode; features: it can only read but not write information. Ram refers to random access memory, which is an internal memory that exchanges data directly with CPU. Features: random access, volatility, sensitivity to static electricity, fast access speed, need to be refreshed.

ROM (read-only memory)

Read-only memory (Read-Only Memory,ROM) operates in a non-destructive readout mode and can only read out information that cannot be written. Once the information is written, it is fixed, and even if the power is cut off, the information will not be lost, so it is also called fixed memory. The data stored in ROM is usually written before loading into the whole machine, and can only be read out during the working process of the whole machine, unlike random access memory (RAM), which can quickly and easily rewrite the storage content. The data stored in ROM is stable, and the data stored after power outage will not change, and the structure is simple and easy to use, so it is often used to store a variety of fixed programs and data.

Characteristics

The characteristic of ROM is that it can only read but not write information. It usually solidifies a basic input / output system called BIOS (basic input / output system) in the ROM of the computer motherboard. Its main function is to complete the power-on self-test of the system, the initialization of each functional module in the system, the basic input / output driver of the system and the boot operating system.

Scope of use

Because ROM has the characteristic of not losing information after power off, it can be used in BIOS chip for computer startup. EPROM, EEPROM and Flash ROM (NOR Flash and NAND Flash) have the same performance as ROM, but can be rewritten. Generally, reading is faster than writing, and writing requires a higher voltage than reading. (reading 5V and writing 12V) but Flash can read and write at the same voltage with large capacity and low cost, such as U disk MP3 is widely used. In computer systems, RAM is generally used as memory, and ROM is generally used as firmware to store some hardware drivers.

RAM (random access memory)

Random access memory (Random Access Memory, abbreviation: RAM), also known as main memory, is an internal memory that exchanges data directly with CPU. It can be read and written at any time (except when refreshed), is fast, and is usually used as a temporary data storage medium for the operating system or other running programs. RAM can write (store) or read (read) information from any specified address at any time while working. The biggest difference between it and ROM is the volatility of data, that is, the data stored in the event of a power outage will be lost. RAM is used in computers and digital systems to temporarily store programs, data, and intermediate results.

Characteristics

1. Random access

The so-called "random access" means that when the data in the memory is read or written, the time required has nothing to do with the location where the information is located or where it is written. In contrast, when reading or writing sequential access (Sequential Access) to information in a storage device, the time required is related to the location. It is mainly used to store operating system, various applications, data and so on.

When RAM is working properly, you can read data from RAM or write data to RAM. Compared with ROM, RAM has the advantages of convenient reading / writing and flexible use, so it is especially suitable for frequent and rapid data change.

2. Volatility

RAM cannot retain data when the power is off. If you need to save data, you must write it to a long-term storage device (such as a hard disk).

The working characteristic of RAM is that after being powered on, the data information can be accessed at any location at any time, and the internal information also disappears after the power is cut off.

3. Sensitive to static electricity

Like other fine integrated circuits, random access memory is very sensitive to the electrostatic charge of the environment. Static electricity will interfere with the charge of the capacitor in the memory, cause data loss, and even burn out the circuit. Therefore, you should touch the metal ground with your hands before touching the random access memory.

4. Access speed

Modern random access memory has the fastest write and read speed of almost all access devices, and the access latency is negligible compared with other storage devices involved in mechanical operation.

5. Need to refresh (regenerate)

Modern random access memories rely on capacitors to store data. When the capacitor is fully charged, it represents 1 (binary), and the uncharged represents 0. As there is more or less leakage of capacitors, if not treated specially, the data will gradually be lost over time. Refresh refers to regularly reading the status of the capacitor, and then recharging the capacitor according to the original state to make up for the lost charge. The need for refresh explains the volatility of random access memory.

These are all the contents of this article entitled "what are the characteristics of ROM and RAM". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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