New variants of SDRAM are DDR1, DDR2, and DDR3. Both random access memory DDR and SDRM are memory integrated circuits which are used in computers.
Traditionally, Dynamic Random Access Memory (DRAM) had the associate asynchronous interface, which suggests that it responds as quickly as potential to changes up to speed inputs. each SDRAM and DDR RAM have a synchronous interface, which means that it waits for a clock signal before responding to regulate inputs and is thus synchronized with the computer’s system bus.
This permits the silicon chip to possess an additional advanced pattern of operation than associate asynchronous DRAM. this can be additionally why the speed of SDRAM and DDR RAM is rated in rate instead of in nanoseconds (ns).
SDRAM typically refers to initial generation Synchronous DRAM, which is slower than resulting generations (DDR) as a result of only 1 word of knowledge is transmitted per clock cycle (single data rate).
The second generation of synchronous DRAM memory chips was DDR (sometimes known as DDR1). DDR stands for double rate, which suggests the chip reads or writes 2 words of knowledge per clock cycle. The DDR interface accomplishes this by reading and writing information on each the rising and falling edges of the clock signal. Additionally, some minor changes to the SDR interface temporal arrangement were created in savvy, and therefore the offer voltage was reduced from three.3 to 2.5 V. As a result, DDR SDRAM isn’t backward compatible with SDR SDRAM.
Difference between DDR and SDRAM:
| SDRAM | DDR |
|---|---|
| It refers as synchronus dynamic random access memory | It refers as Double data rate SDRAM |
| SDRAM has 168 pins and two notches at the connector | DDR has 184 pins and a single notch at the connector. |
| SDRAM was released in 1997 | DDR RAM was released in 2000 |
| SDRAM has less speed in camparison DDR | DDR can transfer data at roughly twice the speed of SDRAM. |
| it’s working on 3.3 volts | it’s working on 2.5 Volts (standard); 1.8 V (low voltage) |
| SDRAM speed is considered as 66 MHz, 100 MHz, 133 MHz | DDR working on speed as 200 MHz, 266 MHz, 333 MHz, 400 MHz |
| SDRAM’s Internal rate range is (100 Mhz-166 Mhz) | DDR’s Internal rate range is(133 Mhz – 200 Mhz) |
| Data rate of SDRAM is (0.8-1.3) GB/s | Data rate of DDR is (2.1-3.2) |
| SDRAM prefetch timing is 1ns | DDR prefetch timing is 2ns |
| SDRAM is waiting wait for the completion of the previous command to be able to do another read/write operation. | DDR is not waiting wait for the completion of the previous command to be able to do another read/write operation. |
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