Extended-height DIMM
An extended-height DIMM for use in a memory system having slots designed to receive DIMMs that comply with a JEDEC standard that specifies a maximum height for the DIMM and a maximum number of devices allowed to reside on the DIMM. The DIMM comprises a PCB having an edge connector designed to mate with a memory system slot and a height which is greater than the maximum height specified in the applicable standard, a plurality of memory devices which exceeds the maximum number of devices specified in the applicable standard, and a memory buffer which operates as an interface between a host controller's data and command/address busses and the memory devices. This arrangement enables the extended-height DIMM to provide greater memory capacity than would a DIMM which complies with the maximum height and maximum number of devices limits.
1. An extended-height DIMM for use in a memory system having slots designed to receive DIMMs that comply with a JEDEC standard that specifies a maximum height for the DIMM and the maximum number of devices allowed to reside on the DIMM, comprising:
a printed circuit board (PCB) having an edge connector designed to mate with a respective one of said memory system slots, the height of said PCB being greater than said maximum height;
a plurality of memory devices on said PCB which exceeds said maximum number of devices; and
a memory buffer on said PCB arranged to operate as an interface between a host controller's data and command/address busses and all of said memory devices;
such that said extended-height DIMM provides greater memory capacity than would a DIMM which complies with said maximum height and maximum number of devices limits.
2. The extended-height DIMM of claim 1 , wherein said maximum height is approximately 30 mm and said PCB has a height of approximately 56 mm.
3. The extended-height DIMM of claim 1 , wherein said maximum number of devices limit is 36 and said PCB can accommodate as many as 72 devices.
4. The extended-height DIMM of claim 1 , wherein said memory devices are planar DRAMs.
5. The extended-height DIMM of claim 4 , wherein the greater number of planar DRAMs accommodated by said extended-height DIMM enable said extended DIMM to provide a memory capacity comparable to that of a DIMM on which stacked DRAMs reside and which is in compliance with said standard.
6. The extended-height DIMM of claim 1 , wherein said memory devices are stacked DRAMs.
7. The extended-height DIMM of claim 1 , wherein said memory buffer is arranged to support up to 8 physical ranks while appearing to said host controller as if there are no more than 4 logical ranks and 1 physical rank.
8. The extended-height DIMM of claim 1 , wherein said slots are designed to receive DIMMs in compliance with the DDR3, DDR3L and DDR3U RDIMM, UDIMM or LRDIMM JEDEC standards.
9. The extended-height DIMM of claim 1 , wherein said memory devices are eight data lane devices.
10. The extended-height DIMM of claim 1 , wherein said memory devices are four data lane devices.
11. The extended-height DIMM of claim 1 , wherein said memory buffer is a JEDEC-compatible memory buffer.