1. An output apparatus which outputs a dot pattern, said output apparatus comprising: connection means for connecting, to said output apparatus, an external apparatus which comprises memory means for storing non-dot data and a program and a central processing unit for generating a dot pattern based on the stored non-dot data and the program; and reading means for, if the external apparatus is connected to said output apparatus by said connection means, reading the generated dot pattern from the external apparatus, and for, if the external apparatus is not connected to said output apparatus, obtaining a dot pattern from pattern information stored within said output apparatus; and output means for outputting the dot pattern read by said reading means, wherein the output apparatus and the external apparatus operate in parallel with each other.