Lecture on ALU and Control Unit Design Presented

ALU Design • Arithmetic Unit • Logic Unit Cin X x 3 x 2

Arithmetic Unit Cin Lets take the following two operations S 0 0 F=X+Y+0 1

Block Diagram of Arithmetic Unit X Y 4 4 Arithmetic Unit 4 S 0

Logic Unit S 0 Operation 0 X AND Y 1 X XOR Y www.

Block Diagram of Logic Unit X Y 4 4 Logic Unit 4 S 0

Block Diagram of ALU 4 Arithmetic Unit 4 Y 4 F Multiplexer X S

Design of the Control Unit • Two types of control unit design – Hardwired

Basic Concepts Transfer to Transfer 14 th bit of Transfer www. assignmrntpoint. com to

Multiplication Using Addition Microprocessor speed depends on bus architecture www. assignmrntpoint. com

Bus Architecture • Three types of bus architectures – Single-bus architecture – Two-bus architecture

Single Bus Architecture www. assignmrntpoint. com

Two-bus Architecture www. assignmrntpoint. com

Timing Signals • One of the main task of control unit is to sequence

Hardwired Control Design • Eight Steps to follow www. assignmrntpoint. com

Start Step 1: Derive the Flow Chart R 0 M Multiplicand via inbus Q

Step 2: Obtain register transfer description www. assignmrntpoint. com

Step 3: Specify processing hardware along with various components www. assignmrntpoint. com

Step 4: Complete the design of the processing section C 0: R ← 0

Step 5: Determine the block diagram of the controller 0 1 2 3 4

Slides: 22

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Lecture on ALU and Control Unit Design Presented By WWW. Assignment. Point. Com www. assignmrntpoint. com

ALU Design • Arithmetic Unit • Logic Unit Cin X x 3 x 2 x 1 x 0 f 3 f 2 f 1 f 0 A 3 A 2 A 1 A 0 4 -bit parallel adder Y y 3 y 2 y 1 y 0 B 3 B 2 B 1 B 0 Cout Arithmetic Unit www. assignmrntpoint. com F

Arithmetic Unit Cin Lets take the following two operations S 0 0 F=X+Y+0 1 F = X – Y = X + (-Y) = X + (Y + 1) = X + Y + 1 Cout 0 MUX 1 y 1 4 -bit parallel adder Cin 1 y 2 X Y x 3 x 2 x 1 x 0 y 3 F 4 -bit parallel adder f 3 f 2 f 1 f 0 F 0 MUX 1 y 0 0 MUX 1 S 0 www. assignmrntpoint. com Cout

Block Diagram of Arithmetic Unit X Y 4 4 Arithmetic Unit 4 S 0 www. assignmrntpoint. com F

Logic Unit S 0 Operation 0 X AND Y 1 X XOR Y www. assignmrntpoint. com

Block Diagram of Logic Unit X Y 4 4 Logic Unit 4 S 0 www. assignmrntpoint. com G

Block Diagram of ALU 4 Arithmetic Unit 4 Y 4 F Multiplexer X S 0 X Y S 0 S 1 4 4 4 Logic Unit 4 www. assignmrntpoint. com G 4 Z

www. assignmrntpoint. com

Design of the Control Unit • Two types of control unit design – Hardwired Control Design – Micro-programmed Control Unit Design www. assignmrntpoint. com

Basic Concepts Transfer to Transfer 14 th bit of Transfer www. assignmrntpoint. com to to 1 st bit of if E is enabled

Multiplication Using Addition Microprocessor speed depends on bus architecture www. assignmrntpoint. com

Bus Architecture • Three types of bus architectures – Single-bus architecture – Two-bus architecture – Three-bus architecture www. assignmrntpoint. com

Single Bus Architecture www. assignmrntpoint. com

Two-bus Architecture www. assignmrntpoint. com

Timing Signals • One of the main task of control unit is to sequence a set of operations properly • Use a ring counter to implement this www. assignmrntpoint. com

Hardwired Control Design • Eight Steps to follow www. assignmrntpoint. com

Start Step 1: Derive the Flow Chart R 0 M Multiplicand via inbus Q Multiplier via inbus R R+M Q Q– 1 no Q=0 yes Outbus R Stop www. assignmrntpoint. com

Step 2: Obtain register transfer description www. assignmrntpoint. com

Step 3: Specify processing hardware along with various components www. assignmrntpoint. com

Step 4: Complete the design of the processing section C 0: R ← 0 C 1: M ← inbus C 2: Q ← inbus C 3: F ← r + l C 4: Q ← Q – 1 C 5: outbus ← R C 6: R ← F 4 4 L M C 1 C L R C D C 0 C 6 Q D 4 L D C 2 C 4 4 -bit adder C 3 Z F www. assignmrntpoint. com C 5

Step 5: Determine the block diagram of the controller 0 1 2 3 4 5 6 www. assignmrntpoint. com