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)