Talk:Serial presence detect

message: http://www.ixbt.com/mainboard/spd.shtml  —Preceding unsigned comment added by 189.4.112.16 (talk) 19:04, 6 November 2007 (UTC)
thread_title:  russian articles 

message: (Some chicken scratches to be turned into an article at some point)
Usually called just presence detect, this used some spare pins on 72-pin SIMMs.  They were either open-circuit (pulled high by motherboard resistors) or shorted to ground.  All pins open meant "no SIMM inserted"
References:
* http://www.mcamafia.de/mcapage0/memorypd.htm
* http://ohlandl.ipv7.net/config/mempresence.html
* http://www.keycruncher.com/blog/2003/12/14/making-standard-simm-s-work-memory-upgrade-on-the-hp-laserjet-6mp-5mp/
* http://www.shawnbehrens.de/hpmem.htm
* http://books.google.com/books?id=E1p2FDL7P5QC&pg=RA1-PA447&lpg=RA1-PA447&dq=SIMM+presence+detect&source=bl&ots=M1ohE6a5bv&sig=i6mI_mE78Bk2hbya3zUByPS3dJE&hl=en&ei=6PwCSpvYKuawtgfZ3-WKBw&sa=X&oi=book_result&ct=result&resnum=6
* Page 448 of the same book
* Page 449
Pins assigned as follows:
* The first 4 bits on pins 67–70 encode the size and speed.
* Pin 72 is the ground pin generally connected to.
* Pin 48 grounded marks an ECC SIMM.  Open marks non-ECC.  Parity is unclear.
* Pin 11 is PS5, for extension
Pins 67-70:
 PPD decode table
PD4 (70)	PD3 (69)	PD2 (68)	PD1 (67)	PD5 (11)	
GND     	GND     	        	        	open    	100 ns
GND     	open    	        	        	        	80 ns
open    	GND     	        	        	        	70 ns
open    	open    	        	        	        	60 ns
GND     	GND     	        	        	GND     	50 ns
        	        	GND     	GND     	GND     	???
        	        	GND     	open    	GND     	32 MB
        	        	open    	GND     	GND     	16 MB
        	        	open    	open    	GND     	???
        	        	GND     	GND     	open    	4 MB
        	        	GND     	open    	open    	2 MB
        	        	open    	GND     	open    	1 MB
        	        	open    	open    	open    	8 MB
Pin 11 mostly changes the capacity, but also causes the 100 ns speed grade to be re-interpreted.
This is the JEDEC encoding, apparently IBM and others made up their own.
71.41.210.146 (talk) 15:57, 7 May 2009 (UTC)
thread_title:  [[Parallel Presence Detect]] notes 

message: What hardware and software would allow ordinary mortals to change the SPD info?
What equipment is used commercially to write and read SPD parameters?
-96.237.10.106 (talk) 23:27, 27 May 2009 (UTC)
thread_title:  SPD information writers 

message: Please add laptop SPD So-DIMM info.
-96.237.10.106 (talk) 02:24, 28 May 2009 (UTC)
thread_title:  SO-DIMM 

message: The detailed DDR1 AND DDR2 parameter tables in the article are very useful -- but we need SDRAM and DDR3 parameter tables also, or good annotation of the existing tables clearly stating what is the same and what is different.
-96.237.5.115 (talk) 02:27, 16 July 2009 (UTC)
thread_title:  SDRAM and DDR3 parameter tables 

message: Does anyone have the time/expertise to add a DDR4 SPD table? 
80.193.214.229 (talk) 11:10, 3 May 2017 (UTC)
thread_title:  DDR4 SPD Table 

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thread_title:  External links modified 

message: Some fields are Binary-coded decimal encoded.
Why ? They don't strike me as intended to be read by humans, and even then the processing power to convert binary to decimal would have been so small.  — Preceding unsigned comment added by Musaran (talk • contribs) 10:49, 31 January 2018 (UTC)
thread_title:  Why BCD ?