Go Differences between RAM, ROM, SRAM, DRAM, Ssram, SDRAM, FLASH, EEPROM

RAM (Random Access memory). The contents of the storage unit can be withdrawn or deposited as required, and the speed of access is independent of the location of the memory unit. This memory loses its stored content when it loses power, so it is mainly used to store short-time use programs. According to the different storage information, the random memory is divided into static random memory (Ram,sram) and dynamic random memory (Ram,dram).

ROM (Read-only memory) is a read-only memory, a solid-state semiconductor memory that can read only the data previously stored. The feature is that once the data is stored, it can no longer be changed or deleted. It is usually used in electronic or computer systems that do not require frequent changes to the data and will not disappear due to power off.

SRAM(Static RAM) does not require a flush circuit to hold the data stored inside it.

DRAM(Dynamic RAM) every once in a while to refresh the charge, otherwise the internal data will disappear.

So SRAM has a high performance, but SRAM also has its shortcomings, that is, its low integration, the same capacity of DRAM memory can be designed for a smaller volume, but SRAM requires a large volume, and power consumption is large. So the SRAM memory on the motherboard occupies a portion of the area.

SRAM has high speed and good performance, it mainly has the following applications:

1) cache between CPU and main memory.

2) CPU internal L1/L2 or external L2 cache.

Ssram(synchronous SRAM) is a synchronous static random access memory. Synchronization refers to the memory work needs synchronous clock, the internal command of the sending and transmission of data are based on it, random refers to the data is not linear storage, but by the specified address to read and write data.

All access to the Ssram is initiated on the rising/falling edge of the clock. The address, data input, and other control signals are related to the clock signal. This is different from asynchronous SRAM, where the access to asynchronous SRAM is independent of the clock, and the data input and output are controlled by the change of address.

SDRAM(synchronous DRAM) is synchronous dynamic random access memory. Synchronization refers to the memory work needs synchronous clock, the internal command of the sending and transmission of data are based on it as a benchmark; dynamic means that the storage array needs to be constantly refreshed to ensure that the data is not lost;

Flash is flash. It is a long-life non-volatile (in the case of a power outage can still hold the stored data information) of the memory, data deletion is not in a single byte units but in fixed chunks (note: NOR Flash for byte storage. ), the chunk size is generally 256KB to 20MB.

An EEPROM is an electronically erasable read-only memory. Unlike flash memory, EEPROM can be deleted and rewritten at byte level instead of the entire chip, so flash memory is faster than EEPROM update. The flash memory is often used to store settings information, such as in the BIOS of the computer (basic input and Output program), PDA (personal digital assistant), digital camera and so on, because it can still save data.

Reference documents:

[1] Original reprint address: http://www.cnblogs.com/cy0904030105/archive/2012/05/02/2479331.html

[2] Extended reading. Sram/dram,prom/eprom/eeprom,nor/nand Flash difference. http://blog.csdn.net/chenlong12580/article/details/44276995

[3] Introduction Nandflash, Norflash, RAM, SRAM, DRAM, ROM, EEPROM, flash the difference. http://blog.csdn.net/dcx1205/article/details/46337451

Go Differences between RAM, ROM, SRAM, DRAM, Ssram, SDRAM, FLASH, EEPROM