The original Xbox shipped with 64MB of RAM – an amount that seems tiny by modern standards but was actually quite a lot for 2001.
Now, a modder called Prehis2oricman has quadrupled the amount of available RAM to 256MB. Previously, modders had been able to increase the memory to 128MB by using the four empty RAM slots on the console's motherboard – these empty slots were used in Xbox dev kits and in Sega's Chihiro arcade standard, which was built on Xbox architecture.
Prehis2oricman's new RAM module is made of two parts – a RAM chip and an interposer, the latter of which allows you to boost the amount of RAM in each memory slot – including the RAM slots which are occupied by the four 16MB RAM slots the console ships with normally. The end result is eight slots filled with 32MB of RAM for a grand total of 256MB.
According to the modder, this new approach "required many months of reverse engineering, hardware engineering, software hacking, and perseverance."
The catch? There's very little reason to install this mod (which is quite difficult) at the moment. The current Xbox BIOS wasn't designed to deal with this much RAM, and therefore there aren't any applications which make use of it. That could change over time, of course, but at the moment, there's little reason to do this mod, outside of having bragging rights.
Given time, we could see a new BIOS being developed by the community which unlocks the additional potential this RAM upgrade delivers, but for now, all we can do is marvel at the level of dedication required to create this amazing technical solution.