Hi all,
Can any one please explain me, what is memory bank in the world of
hardware?
Is a DIMM called as one bank or is it a page in a DIMM?\
Can any one please help me in getting this answered.
It depends on the timeframe of computer history you want to look at.
In
the old days of mainframes & minicomputers it referred to separate stacks
of memory chips with contiguous memory addresses hitting each "bank" in a
round-robin fashion. IOW as you hit the next bank, the previous one which
had just been hit, got a "rest" to prepare for its next access... assuming
sequential memory access patterns of course.
The term bank has also evolved and been misused, either because people did
not keep up with the evolution or because they thought it seemed to fit
what they thought it meant.
In PC terms, at one time a bank was the
minimum memory increment you could use in memory capacity, e.g. you had to
add a "bank" of a pair of 72-pin 32-bit FP/EDO SIMMs at a time for a 64-bit
memory bus. This was also used for the old 30-pin 8-bit SIMMs too, where
(trying to remember that far back) you had to add a bank of 4 SIMMs for the
32-bit memory bus.
When SDRAM came along, the term bank was used by the memory chip designers
for the separately addressable "interleaved" banks of memory on the chips -
the early 32-Mbit SDRAMs had 2 banks, 64Mbit and later ones had 4 banks, as
has all DDR-SDRAM used for PC system memory; 512Mbit DDR2-SDRAM chips have
4 banks and 1Mbit DDR2 chips can have 8. When addressing those chips, one
of the 32-bit CPU address lines is used/routed by the memory controller to
select the bank, during the RAS and CAS cycles. In those terms, a "page"
is a full row, all the columns, of any given row address in one of the the
banks.
When talking of DIMMs with two independently addressable sets of memory
chips, one set on each side of a module, there are still some docs which
refer to that as a dual-bank DIMM *but* due to the conflict with the usage
for internal chip "banks", other terms have been sought. At one time
Intel's docs referred to a "row" of memory chips but it's clear now that
the preferred term is "rank". IOW a DIMM with chips on only one side is a
single-rank DIMM; with chips on both sides -- and independently addressable
-- a dual-rank DIMM.
