What is SDRAM and what does it have to do with memory?

SDRAM, or Synchronous DRAM, was once the most widely used type of memory on PCs, and even today SDRAM still has a place in the market. Since it is a "synchronous DRAM", it means that its working speed is synchronized with the speed of the system bus. SDRAM memory is divided into PC66, PC100, PC133 and other different specifications, and the number after the specification represents the maximum normal system bus speed of the memory, such as PC100, which means that this memory can work synchronously in a computer with a system bus of 100MHz.

Synchronization with the system bus speed, i.e. with the system clock, avoids unnecessary waiting periods and reduces data storage time. Synchronization also lets the memory controller know at which clock pulse period the data request is used, so data can be transmitted as soon as the pulse rises. SDRAM uses a 168-pin DIMM interface with a 64-bit bandwidth.

SDRAM is not only used in memory, but also in video memory.

Now eliminated!

The current memory is mainly DDR, and there used to be a kind of old memory, which was SDRAM, but now it is basically eliminated.

There are two types of memory: SD and DDR. SD is what you call SDRAM Chinese is synchronous dynamic random memory. SD is running out of memory now.

It can only be seen on the P3 machine. There are two ports on the memory. The largest seems to be only 128m

And now the machine I use is all DDR memory. There is only one port on the memory. The smallest should be 128m

1.Performance differences.

1) Compared with SDRAM: DDR uses more advanced synchronization circuitry, so that the main steps of specifying address, data transmission and output can be performed independently, and remain fully synchronized with the CPU.

2) DDR uses DLL (Delay Locked Loop) technology, which can be used by the memory controller to pinpoint the data when it is active, output it every 16 times, and resynchronize the data from different memory modules.

3) DDR essentially does not require an increase in clock frequency to double the speed of SDRAM, it allows data to be read out on the rising and falling edges of the clock pulse, and thus doubles the speed of standard SDRAM.

2.External differences.

1) In terms of form factor, DDR is not much different from SDRAM, they have the same size and pin distance. The standard DDR memory module is a 184-pin line DIMM (double-sided pin memory module). It's a lot like the standard 168-pin Sdram DIMM, but with one notch instead of two notches on the SD.

2) The length of the component is also inches, and it mainly contains new control, clock, power, and ground signals.

3) DDR memory uses the SSTL2 standard that supports voltage, not the LVTTL standard for the voltage used by SDRAM.

The specific differences between SDRAM and DDR are as follows:

1. There is a difference in transmission rate

Traditional SDRAM can only transmit data on the rising edge of the signal, while DDR can only transmit data on the rising and falling edges of the signal, so the DDR memory can transfer twice as much data as SDRAM per clock cycle, which is also the meaning of DDR dual data rate and dual data rate.

2. There are differences in the appearance slots

DDRs differ less from SDRAM in shape and volume, they have similar dimensions and pitches, and the standard DDR memory module is a 184-pin DIMM (double-sided pin memory module). The DDR is very similar to the standard 168-pin SDRAM, with the biggest difference being that the DDR uses only one slot, while the SDRAM uses two.

3. There are differences in design

Compared to SDRAM, DDR employs more advanced synchronization circuitry, which makes the main steps of sending and outgoing specified addresses and data not only independent, but also fully synchronized with the CPU.

DDR uses a delay-lock loop technique, which the memory controller can use to filter the data to pinpoint the data when it is valid, output it every 16 times, and resynchronize the data from the different memory modules.

The difference between SDRAM memory and DIMM memory is that SDRAM memory and DIMM are not the same level of concept. SDRAM refers to the performance aspect of memory, while DIMM refers to the structure of memory. The shape of the slots is not the same.

SDRAM means that memory needs to synchronize the clock for work, and the internal command transmission and data transmission are based on it; Dynamic means that the storage array needs to be constantly refreshed to ensure that data is not lost; Random means that the data is not stored in a linear sequence, but can be read and written at a freely specified address.

DIMM (Dual Inline Memory Module) is quite similar to SIMM (Single In-line Memory Module), except that the two ends of DIMM's gold finger are not interconnected like SIMM, and they transmit signals independently, so they can meet the transmission needs of more data signals.

and DDR are both a type of memory.

SDRAM: synchronous dynamic random access memory, synchronous dynamic random access memory, synchronization means that memory needs to synchronize the clock for work, and the internal command sending and data transmission are based on it; Dynamic means that the storage array needs to be constantly refreshed to ensure that data is not lost; Random means that the data is not stored in a linear sequence, but can be read and written at a freely specified address.