Types of registers based on the data length
64-bit registers - These do not exist in the i586 instruction set. They exist only in the 64-bit processors. Their names start with the R character.
32-bit registers - Their names start with the E character.
16-bit registers
8-bit registers
Categories of registers
- General registers
- Control registers
- Segment registers
Categories of general registers
- Data registers
- Pointer registers
- Index registers
Data registers
There are four data 32-bit data registers: EAX, EBX, ECX, EDX
- Lower halves of the 32-bit registers can be used as four 16-bit data registers: AX, BX, CX and DX.
- Lower and higher halves of the above-mentioned four 16-bit registers can be used as eight 8-bit data registers: AH, AL, BH, BL, CH, CL, DH, and DL.
Regarding the 32-bit processors: There are also four data 64-bit data registers: RAX, RBX, RCX, RDX