PRESENTED BY:-MUHAMMAD

ADEEL RAJPUT

Topic:- Execution Unit (E.U)

Execytion Unit (EU)    E.U unit performs the following

functions. It performs the logic and Arithmetic

operation on memory or register. It receives the instruction from pre

fetch queue and decodes it. It stores the information temporary in

the register array.

Parts of E.U(Execution unit)

Control CircuitALUGeneral Purpose RegisterSpecial Purpose Register2 pointer registers2 index registers

Execution Unit

Control CircuitThe control circuit controls all the operations and flow of data inside the microprocessor.

ALU Arithmetic Logic Unit

This is a 16 bit unit which performs the AND, OR, Exclusive, Addition, Subtraction, Increment, Decrement, Complement and Shift functions.

ALU

General Purpose Register

It has 4 data registers, AX, BX, CX, DX

AX, BX, CX and DX registers has 2 8-bit registers to access the high and low byte data registers. The high byte of AX is called AH and the low byte is AL. Similarly,

General Purpose Register

the high and low bytes of BX, CX, DX are BH and BL, CH and CL, DH and DL respectively.

Flags Register

It is also called status register flags represent result of last

arithmetic or logical instruction executed. Conditional flags are as follows:

1. CF (Carry Flag)

2. AF (Auxiliary Flag)

3. PF (Parity Flag) 

4. ZF (Zero Flag)

Flags Register

5. SF (Sign Flag)

6. OF (Overflow Flag)

Control register

7. TF (Trap Flag):

8. IF (Interrupt Flag):

9. DF (Direction Flag):

And Seven undefined flags register

Pointer and Index Register

2 pointer registers SP, BP SP (Stack pointer) BP (Base pointer) 2 index registers SI, DI SI (Sours index) DI (Destination index)