module computer (a,b,sel,clk,result);
input[7:0] a,b;
input[1:0] sel;
input clk;
output[8:0] result;
reg [8:0] result;
always @ (posedge clk)
reg [1:0] sel;
initial
case (sel)
2'b00:result=a+b;
2'b01:result=a-b;
2'b10:result=a|b;
default:result=a&b;
endcase
endmodule