I have a revision B board. I am running Raspian 2012-12-16 and only 184mbs are allocated. I have successfully run rpi-update but after rebooting I still have 184mb ram. I followed the article here . What else should I try?
As far as I understand it, your RPi (if you updated it successfully) should now have use of all 512mb's. For curiosity sake, maybe also run the following command. Which will make sure that our RPi is updated (NOTE: This will update all installed apps as well)
sudo apt-get update && sudo apt-get upgrade
Check this guide, which says that you need to add the following line to your /boot/config.txt file.
GPU memory in megabyte for the 512MB Raspberry Pi. Ignored by the 256MB RP. Overrides gpu_mem. Max 448. Default not set.
Also have you tried running
sudo raspi-config and seeing if you can adjust the memory split there? (I dont have a 512 RPi, but I remember someone saying that raspi-config knew how to tell the difference)