The latest batch of Raspberry Pi's we have been selling through the shop (manufactured in South Wales, UK) have use a new type of RAM chip.
Previously the Pi used a Samsung chip, they have now switched to using a chip manufactured by Micron marked with 3KA18 D9QHN and an 'M' logo. This chip is visible in the middle of the photo below mounted on top of the processor using their cleaver package-on-package technology. This RAM chip is still 512Mb in size
|Raspberry Pi with new type of RAM chip|
|Older Samsung RAM chip|
To my knowledge there has been no evidence that the new chip give any performance benefit, the change is probably due to cost or logistic reasons.
This new chip requires a firmware update to work. Our current SD card images (e.g oemgateway_24sep2013.img) won't boot with the new RAM; static red PWR LED and nothing else.
To make the Raspberry Pi boot you will need to download the following files and put them in the SD cards FAT (boot) partition overwriting the older files:
Alternative you could download the whole Raspberry Pi firmware repository (95.6Mb) and copy out the files from the boot directory https://github.com/raspberrypi/firmware/archive/master.zip
I'm currently working on getting a new ready-to-go SD card image download uploaded with the changes above included. This should be available to download soon from: http://emoncms.org/site/docs/raspberrypigateway. Look for the 22nd Oct 2013 image.
All SD cards purchased in the shop after today will have the new image which works on the Raspberry Pi's with the new RAM.
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