US Patent 7143200 Semiconductor integrated circuit

A semiconductor integrated circuit to be connected to a PCI bus, having a configuration register. The size of an address space mapped to the semiconductor integrated circuit depends on the size of readable and writable region (Fv) of a base address register (30) that the configuration register has. The size of the readable and writable region of the base address register can be changed by a mask circuit (31). The size of a local address space can be set to be variable according to the number of mask bits specified by a mask signal. For example, also in the case where a plurality of PCI devices are used, a memory space mapped to each device can be selectively reduced in size and as such, it is also possible to cope with the case where finite resources are mapped to many PCI devices to construct a system.