the computer. On a ccNUMA multiprocessor system (Opteron) this includes the memory which is installed in the remote nodes, because the CPUs can directly address (and cache) all memory regardless if it is on the home node or remote. The 1 TB limit (40-bit) for physical memory for the K8 is huge by typical personal computer standards, but might have been a limitation for use in supercomputers. Consequently, the K10 (or "10h") microarchitecture implements 48-bit physical addresses and so can address up to 256 TB of RAM. When there is need, the microarchitecture can be expanded step by step without side-effects from software and simultaneously save cost with its implementation. For future expansion, the architecture supports expanding virtual address space to 64 bits, and physical memory addressing to 52 bits (limited by the page table entry format). This would allow the processor to address 264 bytes (16 exabytes) of virtual address space and 252 bytes (4 petabytes) of physical address space. See also x86-64 64-bit compatibility mode References External links X86 operating modes Programming language implementation de:AMD64#Betriebsmodi