The Execution Unit

Question 1

The Execution Unit consists of:

• a control system ,
• ALU,
• Flag register
• four general purpose registers(AX,BX,CX,DX), -pointer registers (SP,BP) - and Index registers(SI,DI)

where, each register and the ALU is of 16-bits.

Answer 1

The control circuitry controls the internal operations .

Question 2

The decoder in the execution unit decodes the instructions fetched from the memory into a series of actions.

Answer 2

The ALU can:

• add ,
• subtract,
• perform operations like logical AND,OR,XOR,
• increment,
• decrement,
• complement ,
• and shift the binary numbers.