288 Pin DIMMs
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DIMM modules have 288 pins I count... - 64 Address pins - 64 Data pins That adds up to 128 288 - 128 = 160 What are those extra 160 pins used for ? I can imagine, +Volts, Ground, and perhaps clock signals, and perhaps a few other tricks of the trade that I've never heard of before. But, 160 of them ? Duh. Searching on the internet, I found this gang called JEDEC, as well as a zillion other firms. I have so far been unable to find a clear, concise, and simple description of what the pins are for. Interesting Observation: I was unable to find the expansion of the acronym "JEDEC" on their own website. They don't even say what their name is. Duh. Perhaps when I get $6,500.00 they will tell me.
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DIMM modules have 288 pins I count... - 64 Address pins - 64 Data pins That adds up to 128 288 - 128 = 160 What are those extra 160 pins used for ? I can imagine, +Volts, Ground, and perhaps clock signals, and perhaps a few other tricks of the trade that I've never heard of before. But, 160 of them ? Duh. Searching on the internet, I found this gang called JEDEC, as well as a zillion other firms. I have so far been unable to find a clear, concise, and simple description of what the pins are for. Interesting Observation: I was unable to find the expansion of the acronym "JEDEC" on their own website. They don't even say what their name is. Duh. Perhaps when I get $6,500.00 they will tell me.
A DDR4 example datasheet can be found at https://www.micron.com/-/media/client/global/documents/products/data-sheet/modules/parity_rdimm/asf9c512x72pz.pdf[^]. Start on page 5, the pins are arranged in 8 columns. The descriptions of each pin type follows after that.
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DIMM modules have 288 pins I count... - 64 Address pins - 64 Data pins That adds up to 128 288 - 128 = 160 What are those extra 160 pins used for ? I can imagine, +Volts, Ground, and perhaps clock signals, and perhaps a few other tricks of the trade that I've never heard of before. But, 160 of them ? Duh. Searching on the internet, I found this gang called JEDEC, as well as a zillion other firms. I have so far been unable to find a clear, concise, and simple description of what the pins are for. Interesting Observation: I was unable to find the expansion of the acronym "JEDEC" on their own website. They don't even say what their name is. Duh. Perhaps when I get $6,500.00 they will tell me.
The complete list is here: DDR4 SDRAM R[^] - pinouts start on page 5. You'll notice that there are a lot of VSS and VDD pins: these can be thought of as power and ground respectively, and there are probably a lot of 'em because the traces leading to them are so thin and the voltages so low - but that's just a guess.
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DIMM modules have 288 pins I count... - 64 Address pins - 64 Data pins That adds up to 128 288 - 128 = 160 What are those extra 160 pins used for ? I can imagine, +Volts, Ground, and perhaps clock signals, and perhaps a few other tricks of the trade that I've never heard of before. But, 160 of them ? Duh. Searching on the internet, I found this gang called JEDEC, as well as a zillion other firms. I have so far been unable to find a clear, concise, and simple description of what the pins are for. Interesting Observation: I was unable to find the expansion of the acronym "JEDEC" on their own website. They don't even say what their name is. Duh. Perhaps when I get $6,500.00 they will tell me.
I would speculate, the remaing pins are 'ground' to seperate noise. But only speculation :-O [Edit] Or more likely differentially signal lines [Edit01] ChatGPT, take care.. Yes, this is indeed related to differential signals. In DDR4 memory modules, many signals are transmitted as differential signals. This means that the information is not transmitted as single voltages (as with unidirectional signals), but rather as the difference between two voltages. Differential signal transmission offers several advantages, including better noise rejection and higher immunity to electromagnetic interference (EMI). This type of signal transmission is particularly important at high data transfer rates, as is the case with DDR4 memory modules. Therefore, many of the additional pins on a DDR4 DIMM module are reserved for differential signal pairs to ensure reliable and fast data transmission. The ground lines we mentioned earlier also play an important role in providing a stable reference for these differential signals.
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DIMM modules have 288 pins I count... - 64 Address pins - 64 Data pins That adds up to 128 288 - 128 = 160 What are those extra 160 pins used for ? I can imagine, +Volts, Ground, and perhaps clock signals, and perhaps a few other tricks of the trade that I've never heard of before. But, 160 of them ? Duh. Searching on the internet, I found this gang called JEDEC, as well as a zillion other firms. I have so far been unable to find a clear, concise, and simple description of what the pins are for. Interesting Observation: I was unable to find the expansion of the acronym "JEDEC" on their own website. They don't even say what their name is. Duh. Perhaps when I get $6,500.00 they will tell me.
JEDEC is something like "Joint Electron Devices Engineering Council", a very old industry standards body. JEDEC - Wikipedia[^]
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