DDR Memory organization

  • #1
634
1

Main Question or Discussion Point

I was going through the datasheet of 1Gb DDR2 SDRAM. It's organized in rows, columns and banks.
The 1Gb is actually 64Mb*16 datalines.
Which is 8Mb*8 Banks * 16 data lines
I can't figure out how they got 8Mb?

In the datasheet block diagram (attached), there are 13 row address lines. So 2^13 = 8k
there are 8 column addr lines, so 2^8 = 256
8192*256 = 2Mb ???
 

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Answers and Replies

  • #2
uart
Science Advisor
2,776
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Hi likephysics. Each bank is actually organized as 8192 by 256 by 64 bits. There are 10 column select bits, but only 8 of them are used to actually select the column. The remaining 2 are used to select the correct 16 bit word from the 64 bit bank output.
 
  • #3
634
1
uart, Thanks.
One more DDR question - why do you need to precharge a row before selecting it?
 

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