How much unified memory did the Xbox 360 have?

The Xbox 360 had 512 MB of unified GDDR3 memory.

Unlike systems that separate memory into clearly divided pools for the processor and graphics hardware, the Xbox 360 used a unified memory architecture. Its 512 MB of GDDR3 memory operated at 700 MHz and could be shared by the console’s central and graphics processing components according to the needs of games and applications.

The arrangement helped developers allocate memory flexibly, although the total amount was shared across the system rather than being available entirely to graphics. The Xbox 360’s custom graphics processor also included a separate 10 MB embedded DRAM buffer, commonly called eDRAM, for operations such as anti-aliasing.

A frequent mistake is adding the 10 MB eDRAM to the main memory figure and reporting 522 MB. The standard specification is 512 MB of unified GDDR3 RAM; the eDRAM was a separate graphics-related resource, not additional general-purpose system memory.