Why does this file give syntax error in verilog?

Question

My original file has the following

module circuit_320a(A,B,C,D,N,F);
    output N,F;
    input A,B,C,D;
    wire w1,w2,w3,w4;
    and #(30) G1(w1,C,D);
    or #(30) G2(w2,w1,B);
    and #(30) G3(w3,w2,A);
    not #(30) G5(N,c);
    and #(30) G4(w4,B,N);
    or #(30)(F,w3,w4);

endmodule

and my testbench has these

`include "ask.v"

module t_circuit_320a_delay;
    wire N,F;
    reg A,B,C,D;

t_circuit_320a_delay M1 (A,B,C,D,N,F);
initial
  begin
     A=1'b0; B=1'b1; C=1'b0; D=1'b1;
  end

  initial #200 $finish;

   $dumpfile("ask.vcd"); 
   $dumpvars(0, ask_tb);

endmodule

When I try to compile I get syntax errors, why is that?

I have named the original file ask.v and the testbench ask_tb.v

Answer 1

You need to read the FAQ.

Specifically, the $ commands need to be in an initial block, to wit:

`include "ask.v"

module t_circuit_320a_delay;
    wire N,F;
    reg A,B,C,D;

  circuit_320a M1 (A,B,C,D,N,F);

  initial begin
     A=1'b0; B=1'b1; C=1'b0; D=1'b1;
  end

  initial #200 $finish;

  initial begin
    $dumpfile("ask.vcd");
    $dumpvars(0, t_circuit_320a_delay);
  end

endmodule

It will also help if you instantiate the correct module. t_circuit_320a_delay should be instatiating circuit_320a, not itself, and the $dumpvar call needs to refer to t_circuit_320a_delay, not the name of the file.