massively-parallel special-purpose computer for astronomical N-body simulations at National Astronomical Observatory of Japan, we performed a simulation particularly aimed at understanding the boundary conditions for the PC, SG and OG; the relationship among the models; and the current directions.

The organization of this paper is as follows: Section 2 describes the method of our simulation; Section 3 shows the simulation results and describes the structure of the global pulsar magnetosphere; Section 4 discusses the position relationships of the PC, SG, and OG, and summarizes the results of our simulation. Our main conclusion, that both polar-slot gap and OG can exist in a magnetosphere, is also presented in Section 4.

Method of Simulation
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It is necessary to handle formation of the field-aligned electric field $E_{||}$, so that the simulation must not be the usual MHD simulation. A breakthrough can be found by a global particle simulation, which can handle cross-field drift motions due to radiation drag and particle inertia by solving each particle motion. (, hereafter WS) have succeeded in overcoming this heavy computation by using GRAPE. Typical use of GRAPE is for stellar dynamics. However, it should be noted that GRAPE, in which sign-bit is available, can calculate Coulomb 