<Dd> In addition to increasing the size of the general - purpose registers, the number of named general - purpose registers is increased from eight (i.e. eax, ecx, edx, ebx, esp, ebp, esi, edi) in x86 to 16 (i.e. rax, rcx, rdx, rbx, rsp, rbp, rsi, rdi, r8, r9, r10, r11, r12, r13, r14, r15). It is therefore possible to keep more local variables in registers rather than on the stack, and to let registers hold frequently accessed constants; arguments for small and fast subroutines may also be passed in registers to a greater extent . </Dd> <Dd> AMD64 still has fewer registers than many common RISC instruction sets (which typically have 32 registers) or VLIW - like machines such as the IA - 64 (which has 128 registers). However, an AMD64 implementation may have far more internal registers than the number of architectural registers exposed by the instruction set (see register renaming). </Dd> <Dt> Additional XMM (SSE) registers </Dt> <Dd> Similarly, the number of 128 - bit XMM registers (used for Streaming SIMD instructions) is also increased from 8 to 16 . </Dd>

What was the name of the mode invented in november 2013