CPU Registers Flashcards
EAX
It’s called the accumulator register because it’s the primary register used for common calculations (such as ADD and SUB). While other registers can be used for calculations, EAX has been given preferential status by assigning it more efficient, one-byte opcodes.
AX
Least significant 16 bits of EAX
AH
8 most significant bits of AX
AL
8 least significant bits of AX
EBX
In 32-bit architecture, EBX doesn’t really have a special purpose so just think of it as a catch-all for available storage
BX
Least significant 16 bits of EBX
BH
8 most significant bits of BX
BL
8 least significant bits of BX
ECX
The counter register. the counter (or count) register is frequently used as a loop and function repetition counter, though it can also be used to store any data
CX
16 least significant bits of ECX
CH
8 most significant bits of CX
CL
8 least significant bits of CX
EDX
The data register. EDX is kind of like a partner register to EAX. It’s often used in mathematical operations like division and multiplication to deal with overflow where the most significant bits would be stored in EDX and the least significant in EAX. It is also commonly used for storing function variables.
DX
16 least significant bits of EDX
DH
8 most significant bits of DX