Expansion PAK

The Expansion PAK consists of 4 MB (megabytes) of random access memory (RAM)—which is RDRAM, the same type of memory used inside the console itself—increasing the Nintendo 64 console's RAM from 4 MB to 8 MB of contiguous main memory. It is installed in a port on top of the console and replaces the pre-installed Jumper Pak, which is simply a RAMBUS terminator.