Function Table For A 3 Input Alu

A30 and B30. The operations performed by an ALU are controlled by a set of function-select inputs. In this lab you will design a 4-bit ALU with 3 function-select inputs Mode M, Select S1 and S0 inputs. The mode input M selects between a Logic M0 and Arithmetic M1 operation. The functions performed by the ALU are specified in Table I.

This table shows a sample function table for an ALU. All of the arithmetic operations have S. 3 0, and all of the logical operations have S. 3 1. These are the same functions we saw when we built our arithmetic and logic units a few minutes ago. Since our ALU only has 4 logical operations, we don't need S. 2. The operation done

In the proposed design 1, Peres Full Adder Gate PFAG is used in reversible ALU design and HNG gate is used as an adder logic circuit in the proposed ALU design 2.

Arithmetic Logic Unit ALU. In each of the next few slides, the ALU will be considered to have two inputs A and B and one output C. The figure below uses the standard symbol for an ALU. We begin with a very simple three-function ALU and develop the design from there. 1. C A B 2. C A B

one input a other input b if c O, complement of b if c 1 Standard element MUX multiplexor Combined AddSubtract Unit adder Hierarchical design Reuse components Suppose 5 of ALU operations are multiply ops , and other ALU operations take 1 cycle. 0.05 x 32 0.95 x 1 2.55! alu

and implement a 4-bit ALU in an FPGA. Your ALU should have 3 function-select inputs Mode M, Select S1 and S0 inputs. The mode input M selects between an Arithmetic M0 and Logic M1 operation. The functions performed by the ALU are specified in Table 1. Table 1 Functional operation of an ALU Arithmetic Operations Logical Operations

3. Arithmetic-Logic Unit ALU Could try this as an 8 input, 4 output combinational logic problem. 12 Instead - Consider Stages. Depends on 1's or 2's comp arithmetic FA - Full Adder. 13 Control Lines Function. 000 and. 001 or. 010 add. 110 sub. 24

fpga4student.com FPGA projects, Verilog projects, VHDL projects Verilog project Verilog code for ALU by FPGA4STUDENT timescale 1 ns 1 ps module tb_alu Inputs reg 7 0 A, B reg 3 0 ALU_Sel Outputs wire 7 0 ALU_Out wire CarryOut Verilog code for ALU integer i alu test_unit A, B, ALU 8-bit Inputs ALU_Sel

3 ALU control input Function Operations 000 And and 001 Or or 010 Add add, lw, sw 110 Subtract sub, beq 111 Slt slt. CSE 141, S2'06 Jeff Brown Generating ALU control ALU Control Logic Control Truth Table R-format lw sw beq Opcode 000000 100011 101011 000100 RegDst 1 0 x x ALUSrc 0 1 1 0 MemtoReg 0 1 x x RegWrite 1 1 0 0 Outputs MemRead 0 1 0 0

Function Table for ALU Operation Select S3 S2 S1 S0 Cin Operation Function 0 0 0 0 0 F A Transfer A 0 0 0 0 1 F A 1 Increment A 0 0 0 1 0 F A B Addition 0 0 0 1 1 F A B 1 Add with carry 0 0 1 0 0 F A B' Sub with borrow 0 0 1 0 1 F A B' 1 Subtraction 0 0 1 1 0 F A - 1 Decrement A