General purpose registers

The 8086 microprocessor has a total of fourteen registers that are accessible to the programmer. It is divided into four groups. They are:

  • Four General purpose registers
  • Four Index/Pointer registers
  • Four Segment registers
  • Two  Other registers

General purpose registers :

General purpose registers

Accumulator register consists of two 8-bit registers AL and AH, which can be combined together and used as a 16-bit register AX. AL in this case contains the loworder byte of the word, and AH contains the high-order byte. Accumulator can be used for I/O operations and string manipulation. 

Base register consists of two 8-bit registers BL and BH, which can be combined together and used as a 16-bit register BX. BL in this case contains the low-order byte of the word, and BH contains the high-order byte. BX register usually contains a data pointer used for based, based indexed or register indirect addressing.

Count register consists of two 8-bit registers CL and CH, which can be combined together and used as a 16-bit register CX. When combined, CL register contains the loworder byte of the word, and CH contains the high-order byte. Count register can be used in Loop, shift/rotate instructions and as a counter in string manipulation

Data register consists of two 8-bit registers DL and DH, which can be combined together and used as a 16-bit register DX. When combined, DL register contains the low order byte of the word, and DH contains the high-order byte. Data register can be used as a port number in I/O operations. In integer 32-bit multiply and divide instruction the DX register contains high-order word of the initial or resulting number.