[Country EMBED strategy] [039] [I look at the memory from the inside]

Source: Internet
Author: User


Memory classification

1.DRAM (Dynamic RAM)

Its basic original is a small capacitor, the capacitor can be on the bipolar plate to retain the charge, but need to periodically refresh, otherwise the data will be lost. The disadvantage is that the storage media should be refreshed periodically, and the access speed is slow

DRAM classification:

1.1.SDRAM Synchronous Dynamic Random memory

Synchronization: The memory needs to have a synchronous clock, the internal command of the transmission and transfer of data are based on the clock

Dynamic: Storage arrays need constant refreshes to ensure data is not lost

Random: means that data is not stored linearly, but is freely assigned to the address for data reading and writing

1.2.DDR (double Data rate SDRAM double-speed synchronous dynamic random memory)

In addition to transmitting data over the rising edge of the clock pulse, DDR can also transmit data over a falling edge


The DDR2 transfer rate is twice times the DDR transfer rate

2.SRAM (Static RAM)

It is a kind of memory with still access function, and it can save the data stored in it without having to refresh the circuit periodically. The advantage is the fast access speed, but the disadvantage is the power consumption, high cost

Internal memory structure

1. Table structure

The internal memory is like a table, and the data is stored in each cell. When the data read and write, specify the line number, and then specify the column number, you can accurately find the desired cell. This form is called Logical Bank (L-bank). Now a memory chip typically has 4 L-bank

2. Memory addressing

1. Select L-bank 2. Select the line address 3. Select the column address

3. Memory capacity

Memory capacity = L-bank Number * Number of cells * cell capacity

[Country EMBED strategy] [039] [I look at the memory from the inside]

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