I am reading on DDR2 memory from past few days and have got confused with some of the terms involved. I am mainly confused from discrete memory (single DDR2 memory IC) rather than DIMM module which consists of many such discrete ICs.
I understand that double data rate means the data is clocked on both rising and falling edge of clock signal. So, for example, if a 16-bit wide bus DDR2 memory IC is interfaced to a microcontroller (with built-in memory controller) at a clock speed of 200MHz (i.e. clock output from memory controller to DDR2 is 200MHz), how would one calculate the data rate?
As per my understanding, 16-bit bus has 16 data lines, and two data bits are transferred per clock cycle for one data line (for double data rate), meaning effective data rate would be: [No. of data lines (16, bits) x Data bits transferred per data line per clock cycle (2, bits) x Clock rate (200, MHz)] / 8 = 800 MB/s
(of course, I am talking of theoretical calculations only)
Have I got it wrong?
I would really appreciate if someone could please clear my confusions. Thank you.