When images emerged of the back of Xbox Series X,Microsoft's powerful new console, several insiders/journalists had anticipated that the large back slot was being used by developers for debugging games. Two of them, however, retracted today explaining that, according to their sources, it is anexpansion for high-speed mass memory.

According to Brad Sams of the website Thurrott.com and Jez Corden of Windows Central,the "mysterious door" will be used to insert solid state memory that can complement the console's internal SSD, in order to expand the storage capacity of games without sacrificing the performance benefits of the SSD. Expanding the console with an external USB disk would make games much slower than the internal disk, forcing players (or the operating system itself, if done automatically) to move the most used titles to the internal disk while keeping the less-used ones in the slower disk.

But what kind of memory could host the slot? According to Sams and Corden, Microsoft is experimenting with the ability to use CFExpress (CompactFlash Express) memories, which support reading speeds of up to 4 GB/s but are also very expensive:a 64 GB card can cost 200 Euros, and would barely be able to accommodate an AAA game. But it is possible that Microsoft will count on the future price reduction of these memories, as is the case with all new technologies, or even that it wants to produce them herself to keep costs down.

We hope to find out soon if it really will be so: stay tuned!