Memory (RAM) – RAM is short for ‘Random Access Memory’ and while it may sound enigmatic, RAM is one of the most important elements of computing. It is the super-fast and temporary data storage space that a computer needs to access right now or in the next few moments.
DDR vs SDRAM
DDR (DDR1), DDR2, DDR3, DDR4, and DDR5 are newer variations of the older SDRAM. SDRAM and DDR RAM are memory-integrated circuits used in computers. SDRAM is a generic name for many types of DRAM that synchronizes with the microprocessor’s (CPU) clock speed.
DRAM had an asynchronous interface; it responds as quickly as possible to changes in control inputs. Both SDRAM and DDR RAM have a synchronous interface, so it waits for a clock signal before responding to control inputs and is therefore synchronized with the computer’s system bus.
This allows the memory chip to have a more complex pattern of operation than an asynchronous DRAM. This is also why the speed of SDRAM and DDR RAM is rated in MHz rather than in nanoseconds (ns).
SDRAM usually refers to the first generation of synchronous DRAM, so is slower than succeeding generations of DDR because only one word of data is transmitted per clock cycle (single data rate).
The second generation of synchronous DRAM memory chips was DDR (or DDR1).
DDR is short for Double Data Rate. It is a memory that uses both the rising and falling edge of the system clock that has the potential of doubling the speed of the memory. So, the chip reads or writes two words of data per clock cycle. The DDR interface achieves this by reading and writing data on both the rising and falling edges of the clock signal.