The registers are the fastest accessible memory for the CPU. Normally, each core of a CPU has its own set of registers. The most used architectures are x86, x64 (for Desktop PC’s) and A32, A64 (for Embedded Devices).
| Purpose | x86 | x64 | A32 | A64 |
|---|---|---|---|---|
| General Purpose | EAX – EDX, ESI, EDI | RAX – RDX, RSI, RDI, R8 – R15 | R0 – R10 | X0 – X15, X18 – X28 |
| Base Ptr/Frame Ptr | EBP | RBP | R11 (FP) | X29 (FP) |
| Intra Procedure | – | – | R12 | X16, X17 |
| Stack Pointer | ESP | RSP | R13 (SP) | SP |
| Link Register | – | – | R14 (LR) | X30 (LR) |
| Instr. Ptr/Progr. Counter | EIP | RIP | R15 (PC) | PC |