ALU (Data Flow Modeling)

Arithmetic Logic Unit (Data Flow Modeling)

The provided Verilog code represents an Arithmetic Logic Unit (ALU) module.

Alu Description:

• The ALU is responsible for performing arithmetic and logical operations on two 8-bit inputs (A and B) according to a 4-bit control signal (S). Here's a high-level overview of the code:

1. The m4_1 module is a 4-input AND-OR gate that takes four inputs (a, b, c, d) and two select signals (s0, s1), and produces a single output (out). It implements a 4-to-1 multiplexer using AND and OR gates.

2. The lcell module represents a logic cell that consists of an AND gate, OR gate, XOR gate, and a NOT gate. It takes two inputs (a, b) and two select signals (s0, s1), and produces a single output (out).

3. The logicUnit module combines eight instances of lcell to create a unit that performs logical operations on two 8-bit inputs (A, B) based on the select signals (s0, s1). The resulting output is an 8-bit vector (D).

4. The fulladd module represents a full-adder circuit that takes three inputs (a, b, c_in) and produces two outputs (sum, c_out). It calculates the sum of two binary inputs and considers the carry-in (c_in).

5. The m_41 module is similar to m4_1, but it only has three inputs (a, b, c, d) and two select signals (s0, s1). It implements a 4-to-1 multiplexer using AND and OR gates.

6. The arithcell module combines a full-adder (fulladd) and a 4-to-1 multiplexer (m_41) to create an arithmetic cell. It takes five inputs (a, b, s1, s0, c_in) and produces two outputs (out, c_out). It performs arithmetic operations on two binary inputs (a, b) based on the select signals (s0, s1) and considers the carry-in (c_in).

7. The arithunit module combines eight instances of arithcell to create an arithmetic unit. It performs arithmetic operations on two 8-bit inputs (A, B) using the select signals (s0, s1) and considers the carry-in (C_in). The resulting output is an 8-bit vector (D) along with a carry-out (C_out) and zero flag (z).

8. The alu module combines a logical unit (logicUnit) and an arithmetic unit (arithunit) to create the full ALU. It takes two 8-bit inputs (A, B), a carry-in (C_in), and a control signal (S). It produces an 8-bit output (D) along with a carry-out (C_out) and zero flag (z).

9. Finally, the Alu_tb module is a testbench that verifies the functionality of the ALU. It sets the inputs (A, B, C_in, S) and monitors the outputs (D, C_out, z) at specific simulation time intervals.

Output

References

• Data Flow Modeling
• Arithmetic logic unit
• Verilog Simulation Basics