Yes, I know. However, since the datasheet did not say that the SDRAM is a DDR then I assumed that it is an SDR.
---
Single data rate (SDR) SDRAM is the older type of memory, commonly used in computers prior to 2002.
Double data rate (DDR) SDRAM hit the mainstream computer market around 2002 and is a straightforward evolution from SDR SDRAM. The most significant difference between DDR and SDR is that DDR reads data on both the rising and falling edges of the clock signal, enabling a DDR memory module to transfer data twice as fast as an SDR memory module.
SOURCE: crucial<dot>com -- I can't post links without the moderator checking the content for now.