Dynamic configuration of memory module using presence detect data

• US 6,381,685 B2
• Filed: 12/28/2000
• Issued: 04/30/2002
• Est. Priority Date: 04/28/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Dell, Timothy Jay, Kellogg, Mark William
• Primary Examiner(s): Yoo, Do Hyun
• Assistant Examiner(s): Namazi, Mehdi
• Application Number:
  US09/750,521
• Publication Number:
  US 20010000822A1
• Time in Patent Office: 488 Days
• Field of Search: 711/5, 711/170-172, 711/103, 711/115, 713/1, 713/2
• US Class Current: 711/170
• CPC Class Codes: G06F 13/1694 Configuration of memory controller to different memory types
• CPC Class Codes: G11C 5/06 Arrangements for interconnecting storage elements electrically, e.g. by wiring
• CPC Class Codes: G11C 7/1045 Read-write mode select circuits

Abstract

A memory module includes a plurality of memory chips on the module; first logic for configuring the memory module to operate in a selectable mode; second logic for storing initial presence detect (PD) data; and third logic for storing modified PD data that corresponds to a requested mode of operation of the memory module received from a system controller. The system checks the first logic to see if the mode is compatible with the system mode. If not, different PD data is written to and read from the third logic successively until a compatible mode is found or the available PD data is exhausted.

Claims

1. A memory module comprising:

a plurality of memory chips on the module;

first logic for configuring the memory module to operate in a selectable mode;

second logic for storing initial presence detect (PD) data; and

third logic for storing modified PD data that corresponds to a requested mode of operation of the memory module received from a system controller and wherein said second logic comprises a non-volatile memory and said third logic comprises a volatile memory; and

further wherein a system controller operates to read the initial PD data and to write modified PD data to said volatile memory;

said modified PD data corresponding to a requested operating mode of the memory module by the system controller;

said first logic operating to accept said modified PD data when the requested operating mode is available in the memory module and write other modified PD data to said volatile memory when said request mode is not available.

2. The apparatus of claim 1 wherein said PD data is accessed with a serial bus controller that interfaces with the system controller.

3. The apparatus of claim 1 wherein said second logic comprises an EEPROM that stores original serial PD data.

4. The apparatus of claim 1 wherein said first logic comprises an ASIC (application specific integrated circuit) logic device and includes a non-volatile memory that stores original serial PD data.

5. The apparatus of claim 1 comprising an I2C bus controller and an I2C bus;

said system controller reading serial PD data from a non-volatile memory after memory power up, and determining compatibility of memory module functions with system requirements.

6. The apparatus of claim 1 wherein said system controller writes the modified PD data to said volatile memory that corresponds to a desired operating mode of the memory module based on system requirements.

7. The apparatus of claim 6 wherein said first logic operates to accept said modified PD data when the corresponding requested mode is available in the module and writes modified SPD data (serial PD data) when the requested mode is not available, said first logic and a system controller operating to effect a dynamic negotiation of a compatible operating mode.

8. The apparatus of claim 1 comprising a serial bus and serial bus controller for interfacing a system controller with the memory module so that the system controller can read and write serial PD data of the memory module to negotiate an operating mode for the memory module.

9. A computer system comprising:

a system controller and a memory module;

the memory module comprising a plurality of memory chips on the module, and a memory module logic circuit for configuring the memory module to operate in a selectable mode;

said system controller negotiating an operating mode of the memory module by reading and writing presence detect (PD) data of the memory module.

10. The computer of claim 9 comprising a serial bus controller for interfacing the memory module with the system controller;

and wherein said system controller operates to read and write serial PD data of the memory module.

11. The computer of claim 9 wherein said memory module comprises a volatile memory that stores modified PD data written by said system controller that corresponds to a requested operating mode, and a non-volatile memory that stores initial PD data.

12. The apparatus of claim 11 wherein said memory module comprises a logic circuit that accepts said modified PD data when the requested operating mode is available in the memory module, and controls the transfer of PD data from said volatile and non-volatile memories based on which memory stores up-to-date data with respect to each PD data entry.

14. The apparatus of claim 9 wherein said selectable mode comprises an address re-mapping function.

13. A method for system control of an intelligent memory module, comprising:

a) reading initial presence detect (PD) data from a non-volatile memory on the memory module;

b) writing modified PD data to a volatile memory based on requested operating mode; and

c) controlling transfer of the modified PD data between the memory module and the system controller based on which memory stores the up-to-date PD data and wherein a logic circuit sets a flag for each PD data entry that is modified in response to a request for a programmable mode from the system controller.

15. The method of claim 13 wherein said requested operating mode comprises an address re-mapping function.

16. The method of claim 13 comprising a multiple step negotiation between the system controller and the memory module by using both circuits to write the modified PD data to the volatile memory until a compatible mode is found or until support lists are exhausted.

17. A method for system control of an intelligent memory module wherein there is a pool of presence detect (PD) data in a computer system, comprising:

a) reading initial presence detect (PD) data from a non-volatile memory on the memory module;

b) determining if the presence detect (PD) data read from the non-volatile memory matches the system requirements;

c) if a match, booting the computer system;

d) if not a match, writing modified PD data from said pool of presence detect (PD) data to a volatile memory based on requested operating mode;

e) reading the modified presence detect (PD) data in the volatile memory;

f) if there is a match, booting the computer system;

g) if there is not a match, repeating steps d) and e), repeatedly until there is a match or until there are no additional presence detect (PD) data in the pool to write.

18. The invention as defined in claim 17 wherein said pool of presence detect data is stored in one of said computer system or on said intelligent memory module.

19. The invention as defined in claim 17 wherein said pool of presence detect (PD) data is stored in both the computer system and said intelligent memory module.

20. The invention as defined in claim 19 wherein the presence detect data described in step g) is written alternately from the presence detect (PD) data in the system and on the intelligent memory module.