Can anyone specifically talk about the model of memory, its characteristics, and the differences bet

DDR belongs to the 1st generation memory, DDR2 belongs to the 2nd generation memory, and DDR3 belongs to the 3rd generation memory. They differ in frequency, voltage, number of pins, and interface location.

1, DDR = double data rate, DDR SDRAM = double rate synchronous dynamic random access memory, people are used to calling DDR, DDR memory is developed on the basis of SDRAM memory, still using SDRAM production system, so for memory manufacturers, only need to make a little improvement to the equipment that manufactures ordinary SDRAM, you can achieve the production of DDR memory.

2,DDR2 DDR II (Double Data Rate 2) SDRAM is a new generation of memory technology standard developed by JEDEC, and the biggest difference between it and the previous generation DDR memory technology standard is that although it also adopts the basic method of data transmission at the same time on the rising and falling edges of the clock, DDR2 memory has twice the pre-read ability of the previous generation DDR memory.

3, DDR3 is a computer memory specification. It is part of the SDRAM family of memory products, which offers higher performance and lower voltage than DDR2 SDRAM, and is the successor to DDR2 SDRAM (Synchronous Dynamic Random Access Memory) (up to eight times) and is also a popular memory product specification.

The difference between DDR and DDR2;

1. As can be seen from the table above, DDR2 actually operates twice as often as DDR at the same core frequency, thanks to the fact that DDR2 memory has twice the 4-bit pre-read capability of standard DDR memory.

2. Although DDR2 and DDR both adopt the basic method of data transmission at the same time in the rising and falling delays of the clock, DDR2 has twice the ability of DDR to pre-read system command data, and the actual frequency of DDR2 is 200MHz under the same working frequency of 100MHz, while DDR2 can reach 400MHz.

3. In DDR and DDR2 memory with the same operating frequency, the memory delay of the latter is slower than that of the former, for example, DDR 200 and DDR2-400 have the same latency, while the latter has twice the bandwidth.

The main differences between DDR2 and DDR3;

1. Since the prefetch of DDR3 is 8bit, the burst length (BL) is also fixed at 8, and for DDR2 and early DDR architecture systems, BL=4 is also commonly used.

2. DDR3 adds a 4-bit burst chop mode to this end, that is, a BL=4 read operation plus a BL=4 write operation is used to synthesize a BL=8 data burst transmission, and this burst mode can be controlled by the A12 address line.

3, and it should be noted that any burst interrupt operation will be prohibited in DDR3 memory and will not be supported, and will be replaced by more flexible burst transfer control (e.g. 4-bit sequential bursting).

There are two basic types of reservoirs: ROM and RAM.

ROM (Read-Only Memory): In a ROM, read-only data is pre-recorded and cannot be moved. ROMs are not easy to lose, that is, they retain their contents regardless of whether the computer is powered on or off.

Most PCs have small ROMs that are primarily used to store critical programs, such as those used to boot up the computer. In addition, ROMs are also used in calculators and peripherals, such as laser printers, where fonts are stored. There are also some extended variables in the ROMs, such as programmable read-only memory (PROM), which uses a dedicated PROM programmer to write data on a blank chip.

RAM (Random Access): The contents of this memory can be accessed (read, written, and moved) in any order. This is in contrast to time-series memory devices, such as tapes, records, etc., where the mechanical movement of the storage medium forces the computer to access data in a fixed order.

RAM is usually responsible for the main storage tasks in a computer, such as the storage of dynamic information such as data and programs. Common formats for RAM include: SRAM (Static RAM) and DRAM (Dynamic RAM).

RAM ICs are usually assembled as sockets. Common standard slot types include: SIMM (Single In-Line Memory Module) slot and DIMM (Dual In-Line Memory Module) slot.

In addition, there are memory types such as Flash Memory, NVRAM, and EEPROM, which are obtained by combining RAM and ROM features.