When writing to dynamic memory, the row address first latches RAS to the chip, then the column address latches CAS to the chip, WE is valid, write data, then the written data is stored in the specified cell.
When the dynamic memory is read out, the CPU first outputs the RAS latch signal to obtain the row address of the data storage unit, and then outputs the CAS latch signal to obtain the column address of the data storage unit, and maintains WE = 1, it can read the data in the storage unit with a known row address.
Memory works as follows:
1. Read-only memory
At the time of manufacture, information (data or programs) is stored and stored permanently. This information can only be read out, generally cannot be written, even if the machine power outage, this data will not be lost.
2. Random Access memory
The RAM representation can either read or write data from it. When the machine is powered off, the data stored in it will be lost.
3. Cache
When the CPU writes or reads data into memory, the data is stored in the cache.
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Extended information:
The difference between memory DDR2 and DDR
1, the highest standard frequency is different.
The starting frequency of DDR2 memory starts from the highest standard frequency of DDR memory 400Mhz, and the frequency that can be produced has been defined to support 533Mhz to 667Mhz, the standard operating frequency is 200\/266\/333MHz, and the operating voltage is 1.8V. DDR2 uses the newly defined 240-pin DIMM interface standard, which is completely incompatible with DDR's 184-PIN DIMM interface standard.
2. Different data transmission methods.
DDR2 and DDR use the same basic method of data transmission in the clock up and down, but the biggest difference is that DDR2 memory can perform 4-bit preread. Double the 2-bit prefetch of standard DDR memory, which means that DDR2 has two zhidao times the preread system command data capability of DDR, so DDR2 simply gets twice the full data transmission capability of DDR.
A chip is an integrated circuit that consists of a large number of transistors. Different chips have different integration scales, up to several hundred million; As small as tens or hundreds of transistors.
Transistors have two states, on and off, represented by 1s and 0s. Multiple transistors produce multiple signals of 1s and 0s that are programmed to perform specific functions (i.e., instructions and data) to represent or process letters, numbers, colors, graphics, etc.
After the chip is powered on, it first generates a start instruction to start the chip, and then it continuously accepts new instructions and data to complete the function.
He uses binary processing.