module tb7new; // testbench for the 6-bit by 4-bit multiplier
               // random inputs, decimal values including a check

reg  [5:0] x; //  6-bit inputs (to be chosen randomly)
reg  [3:0] y; //  4-bit inputs (to be chosen randomly)
wire [9:0] p;     // 10-bit output of the multiplier circuit
reg  [9:0] check; // 10-bit product value used to check correctess

// instantiate the 6-bit by 4-bit multiplier
mult6by4 mult_instance(x, y, p);

// simulation of 20 random multiplication operations
initial repeat (20) begin
    // get new operand values and compute a check value
    x = $random; y = $random;
    check = x * y;

    // compute and display the product every 10 time units
    #10 $display($time, "  %d * %d = %d (%d)", x, y, p, check);
end

endmodule