Simulating a different number of memory circuit devices

• US 8,359,187 B2
• Filed: 07/31/2006
• Issued: 01/22/2013
• Est. Priority Date: 06/24/2005
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Rajan, Suresh Natarajan, Schakel, Keith R., Smith, Michael John Sebastian, Wang, David T., Weber, Frederick Daniel
• Primary Examiner(s): Thangavelu, Kandasamy
• Assistant Examiner(s): OSBORNE, LUKE R
• Application Number:
  US11/461,420
• Publication Number:
  US 20080027702A1
• Time in Patent Office: 2,367 Days
• Field of Search: 703/23, 703/14, 703/15, 703/21, 711/2, 711/5, 711/6, 711/103, 711/101, 711/102, 365/230, 365/230.06, 365/230.08, 365/200
• US Class Current: 703/23
• CPC Class Codes: G11C 11/406 Management or control of the refreshing or charge-regeneration cycles
• CPC Class Codes: G11C 11/40618 Refresh operations over multiple banks or interleaving
• CPC Class Codes: G11C 7/10 Input/output [I/O] data interface arrangements, e.g. I/O data control circuits, I/O data buffers

Abstract

A system and method are provided for simulating a different number of memory circuits. Included is an interface circuit in communication with a first number of memory circuits and a system. Such interface circuit is operable to interface the memory circuits and the system for simulating at least one memory circuit of a second number. Further, the interface circuit interfaces a majority of address or control signals of the memory circuits.

Claims

1. An apparatus, comprising:

an interface circuit operable to communicate with a first number of separate physical memory circuit devices and a system,

wherein the interface circuit is operable to;

present to the system a second number of simulated memory circuit devices such that the first number of physical memory circuit devices appear to the system as the second number of simulated memory circuit devices, wherein presenting the simulated memory circuit devices to the system includes simulating one or more mode register operation control signals, and wherein the second number is less than the first number;

receive, from the system, address or control signals sent to the second number of simulated memory circuit devices for performing one or more operations on the second number of simulated memory circuit devices;

communicate the address or control signals to the first number of memory circuit devices;

present to the system a first column address strobe (CAS) latency associated with each simulated memory circuit device, wherein the first CAS latency is a higher value than a second CAS latency associated with each physical memory circuit device;

receive, from a memory controller of the system, write commands sent to the second number of simulated memory circuit devices; and

delay communicating the write commands to the first number of physical memory circuit devices by an amount of time equal to the difference between the first CAS latency and the second CAS latency.

2. The apparatus of claim 1, wherein the second number is one.

3. The apparatus of claim 1, wherein each of the physical memory circuit devices has a corresponding first memory capacity, and each simulated memory circuit device has a corresponding second memory capacity, where the second memory capacity is greater than the first memory capacity.

4. The apparatus of claim 1, wherein the interface circuit is operable to interface all of the address or control signals between the first number of physical memory circuit devices and the system.

5. The apparatus of claim 1, wherein the interface circuit is operable to interface a majority of the address signals between the first number of physical memory circuit devices and the system.

6. The apparatus of claim 1, wherein the interface circuit is operable to interface a majority of the control signals between the first number of physical memory circuit devices and the system.

7. The apparatus of claim 1, wherein the interface circuit is operable to interface the first number of physical memory circuit devices in order to perform an electrical simulation.

8. The apparatus of claim 1, wherein the interface circuit is operable to interface the first number of physical memory circuit devices in order to perform a logical simulation.

9. The apparatus of claim 1, wherein the interface circuit includes a buffer chip.

10. The apparatus of claim 1, wherein the interface circuit is positioned on a dual in-line memory module (DIMM).

11. The apparatus of claim 10, wherein the DIMM is a small outline-DIMM (SO-DIMM).

12. The apparatus of claim 10, wherein the DIMM is a fully buffered-DIMM (FB-DIMM).

13. The apparatus of claim 10, wherein the DIMM is an un-buffered DIMM.

14. The apparatus of claim 10, wherein the DIMM is a registered-DIMM (R-DIMM).

15. The apparatus of claim 1, wherein each physical memory circuit device includes dynamic random access memory (DRAM).

16. The apparatus of claim 15, wherein each physical memory circuit device includes a monolithic DRAM.

17. The apparatus of claim 16, wherein the interface circuit is in a stack that includes the first number of physical memory circuit devices.

18. The apparatus of claim 17, wherein the stack is a buffered stack.

19. The apparatus of claim 1, wherein the mode register operation is a mode register write operation.

20. The apparatus of claim 1, wherein the mode register operation is a mode register read operation.

21. The apparatus of claim 1, wherein the interface circuit is operable to modify the one or more mode register operations.

22. The apparatus of claim 1, wherein the interface circuit is operable to create two mode-register commands from a single mode register command.

23. The apparatus of claim 1, wherein the interface circuit includes one or more registers.

24. The apparatus of claim 1, wherein the interface circuit is operable to interface one or more data signals between the first number of memory circuit devices and the system.

25. The apparatus of claim 1, wherein the interface circuit includes a first component of a first type and a second component of a second different type.

26. The apparatus of claim 25, wherein the first component is a register and the second component is a buffer.

27. The apparatus of claim 25, wherein the first component is operable to receive from the system one or more control signals intended for the second number of simulated memory circuit devices.

28. The apparatus of claim 25, wherein the second component is operable to receive from the system one or more data signals intended for the second number of simulated memory circuit devices.

29. The apparatus of claim 1, wherein the interface circuit is operable to perform additional functions for presenting the simulated memory circuit devices to the system, wherein the time difference between the first CAS latency and the second CAS latency is sufficient for the interface circuit to perform the additional functions.

30. The apparatus of claim 1, wherein the first CAS latency is a whole number of clock cycles above the second CAS latency.

31. The apparatus of claim 1, wherein the first CAS latency is not a whole number of clock cycles above the second CAS latency.

32. The apparatus of claim 1, wherein the first CAS latency is at least two clock cycles above the second CAS latency.

33. A method, comprising:

presenting to a system a first number of simulated memory circuit devices;

receiving, from the system, address or control signals sent to the first number of simulated memory circuit devices;

communicating the address or control signals to a second number of separate physical memory circuit devices, wherein the first number is less than the second number, and wherein presenting the simulated memory circuit devices to the system includes simulating one or more control signals including one or more mode register operations;

presenting to the system a first column address strobe (CAS) latency associated with each simulated memory circuit device, wherein the first CAS latency is a higher value than a second CAS latency associated with each physical memory circuit device;

receiving, from a memory controller of the system, write commands sent to the first number of simulated memory circuit devices; and

delaying communicating the write commands to the second number of separate physical memory circuit devices by an amount of time equal to the difference between the first CAS latency and the second CAS latency.

34. The method of claim 33, further comprising:

receiving, at a first component between the system and the second number of physical memory circuit devices, the address or control signals; and

sending, to a second different component between the system and the second number of physical memory circuit devices, at least one of the control signals.

35. The method of claim 33, wherein the mode register operation is a mode register write operation.

36. The method of claim 33, wherein the mode register operation is a mode register read operation.

37. A memory module, comprising:

a first number of separate physical memory circuit devices; and

an interface circuit operable to;

interface the first number of physical memory circuit devices and a system in order to present to the system a second number of simulated memory circuit devices, wherein the second number is less than the first number, and wherein presenting to the system the second number of simulated memory circuit devices includes simulating one or more mode register operation control signals;

receive, from the system, address or control signals sent to the second number of simulated memory circuit devices;

communicate the address or control signals to the first number of physical memory circuit devices;

present to the system a first column address strobe (CAS) latency associated with each simulated memory circuit device, wherein the first CAS latency is a higher value than a second CAS latency associated with each physical memory circuit device;

receive, from a memory controller of the system, write commands sent to the second number of simulated memory circuit devices; and

delay communicating the write commands to the first number of physical memory circuit devices by an amount of time equal to the difference between the first CAS latency and the second CAS latency.

38. The memory module of claim 37, wherein simulating the mode register operation includes simulating a mode register write operation.

39. The memory module of claim 37, wherein the interface circuit includes a register and a buffer, and the register is operable to:

receive from the system a control signal intended for the second number of simulated memory circuit devices; and

send the control signal intended for the second number of simulated memory circuit devices to a buffer.