A virtualization mechanism in a first computer of the plurality of computers generates at least one virtual computer on the first computer. Two fitting faces formed on each of the stays are fixed onto a front edge and a member bracket of a front side member. The printing apparatus can execute a back face printing easily, and has good workability. Each bump pad on one electronic device is electrically connected to a corresponding bump pad on the other device by superimposition. Other embodiments are also disclosed and claimed.