What is Rank?
A memory rank is a set of DRAM chips connected to the same chip select. The memory controller may perform read/write operation on the chips in 1 rank. The chips in 1 rank also shares the same control signals. For the current computers, 1 channel has a width of 64bit and can read/write 8 byte of data. For the memory controllers with ECC features and ECC memory modules, 1 channel has a width of 72 bit.
Rank can be determined by the memory controller and the specification of DRAM chips rather than the number of chips. Moreover, rank is not related to whether the memory module is single or dual in-line. Currently, most of the home PC memory controllers have channels with 64-bit width and their DRAM chips have a width of 8 bit. Thus, taking 8 DRAM chips in parallel can satisfy the demand of the memory controllers, 1 rank. However, there are some memory modules made with DRAM chips with 16-bit width. That is, 4 chips is 1 rank. (Please refer to the description below)
Rank: (defined by JEDEC)
A memory rank is simply a unique, independently addressable 64-bit data area of a memory module
Rank can be determined by the memory controller and the specification of DRAM chips rather than the number of chips. Moreover, rank is not related to whether the memory module is single or dual in-line. Currently, most of the home PC memory controllers have channels with 64-bit width and their DRAM chips have a width of 8 bit. Thus, taking 8 DRAM chips in parallel can satisfy the demand of the memory controllers, 1 rank. However, there are some memory modules made with DRAM chips with 16-bit width. That is, 4 chips is 1 rank. (Please refer to the description below)
Rank: (defined by JEDEC)
A memory rank is simply a unique, independently addressable 64-bit data area of a memory module
