He who has most registers win
The registers in the CPU that is often the operands of the mnemonics. Some registers are be accessed in different sizes. That is done by adding a prefix of e for 32 bit and r for 64 bit.
General purpose registers (A-D)
Each of this can be used in larger sizes with ex EAX and RAX.It is also possible to get the lower byte of the 16 bit part with a L (AL) and the higher byte with a H (AH).
- AX : Accumulator
- BX : Base
- CX : Counter
- DX : Data
General Purpose Registers (R8-R15)
64 bits. R8 is full register, R8D is lower 32 bit, R8W is lower 16 bit and R9B is lower 8 bit.
Instruction pointer (ip)
Address of the next instruction. Not modified directly.