HP DC71XX, DX61XX Table, SPD Address Map (SDRAM DIMM)

Processor/Memory Subsystem

The SPD address map is shown in Table 3-2.

Table 3-2

SPD Address Map (SDRAM DIMM)

Byte	Description	Notes	Byte	Description	Notes
0	No. of Bytes Written Into EEPROM	[1]	25	Min. CLK Cycle Time at CL X-2	[7]
1	Total Bytes (#) In EEPROM	[2]	26	Max. Acc. Time From CLK @ CL X-2	[7]
2	Memory Type		27	Min. Row Prechge. Time	[7]
3	No. of Row Addresses On DIMM	[3]	28	Min. Row Active to Delay	[7]
4	No. of Column Addresses On DIMM		29	Min. RAS to CAS Delay	[7]
5	No. of Module Banks On DIMM		30-31	Reserved
6, 7	Data Width of Module		32-61	Superset Data	[7]
8	Voltage Interface Standard of DIMM		62	SPD Revision	[7]
9	Cycletime @ Max CAS Latency (CL)	[4]	63	Checksum Bytes 0-62
10	Access From Clock	[4]	64-71	JEP-106E ID Code	[8]
11	Config. Type (Parity, Nonparity...)		72	DIMM OEM Location	[8]
12	Refresh Rate/Type	[4][5]	73-90	OEM’s Part Number	[8]
13	Width, Primary DRAM		91-92	OEM’s Rev. Code	[8]
14	Error Checking Data Width		93-94	Manufacture Date	[8]
15	Min. Clock Delay	[6]	95-98	OEM’s Assembly S/N	[8]
16	Burst Lengths Supported		99-	OEM Specific Data	[8]
			125
17	No. of Banks For Each Mem. Device	[4]	126	Intel frequency check
18	CAS Latencies Supported	[4]	127	Reserved
19	CS# Latency	[4]	128 - 131	Compaq header “CPQ1”	[9]
20	Write Latency	[4]	132	Header checksum	[9]
21	DIMM Attributes		133 - 145	Unit serial number	[9][10]
22	Memory Device Attributes		146	DIMM ID	[9][11]
23	Min. CLK Cycle Time at CL X-1	[7]	147	Checksum	[9]
24	Max. Acc. Time From CLK @ CL X-1	[7]	148	Reserved	[9]

NOTES:

[1]Programmed as 128 bytes by the DIMM OEM

[2]Must be programmed to 256 bytes.

[3]High order bit defines redundant addressing: if set (1), highest order RAS# address must be re-sent as highest order CAS# address.

[4]Refer to memory manufacturer’s datasheet

[5]MSb is Self Refresh flag. If set (1), assembly supports self refresh.

[6]Back-to-back random column addresses.

[7]Field format proposed to JEDEC but not defined as standard at publication time.

[8]Field specified as optional by JEDEC but required by this system.

[9]HP usage. This system requires that the DIMM EEPROM have this space available for reads/writes.

[10]Serial # in ASCII format (MSB is 133). Intended as backup identifier in case vender data is invalid.

Can also be used to indicate s/n mismatch and flag system adminstrator of possible system Tampering. [11]Contains the socket # of the module (first module is “1”). Intended as backup identifier (refer to note [10]).

3-6 361834-002 Technical Reference Guide