I am implementing factory design pattern in Scala and got a compilation error when i tried to access child class method

 abstract class Computers{
    def hdd:String
    def RAM:String
    def CPU:String
  } 
   class PC(storage:String,memory:String,Cores:String) extends Computers{
   def display:String="This is PC"
    var device="PC"
    def hdd={
      "Hard disk"+" "+storage 
    }
    def RAM={
     memory
    }
    def CPU={
     Cores
    }
  }
   class LAPTOP(storage:String,memory:String,Cores:String) extends Computers{
    def see:String={
      "Hi All"
    }
    var device="Laptop"
    def hdd={
     storage
    }
    def RAM={
     device +":" +memory+" RAM"
    }
    def CPU={
      Cores
    }
  }
  object Computers{    
    def apply(compType:String,storage:String,memory:String,Cores:String)={
      compType match{
        case "PC"=>new PC(storage:String,memory:String,Cores:String)
        case "LAPTOP"=>new LAPTOP(storage:String,memory:String,Cores:String)
      }
    }  
    def main(args:Array[String]){
      val c1=Computers("PC","1 TB","12 GB","5 GHz")
      val c2=Computers("LAPTOP","1 TB","12 GB","5 GHz")
      println(c1.display)
      println(c1.hdd)
      println(c2.RAM)

    }
    
  }

Hi All,i am new to scala and tried to implement factory design pattern. But when i tried to call child class method (display method of PC class)got below compilation error : 'Value display is not a member of Computers' Can some one help why i am getting the error