Kabushiki Kaisha Toshiba

Nobuhiro Takiguchi

Yasuo Yamada

Akira Kanuma

Soichi Kawasaki

A processor includes a bank-structured memory and is capable of handling multiple interrupts. The processor includes a central processing unit (CPU) comprising a plurality of data memories serving as general-purpose registers, and a plurality of bank specifying registers for use in specifying an address to save and restore data without involving an external system bus which connects the CPU and a program memory, such as a built-in read only memory (ROM), for storing a user program. The processor further includes a bank structured memory, connected to the CPU via an exclusive-use data bus, for holding data stored in the data memories using the bank specifying registers and for returning data stored in the bank structural memory to the data memories using the bank specifying registers. The bank specifying registers include a current bank pointer (CBP) or register for indicating a position of a bank presently in use, and a previous bank pointer (PBP) or register for indicating a bank position of data to be returned to the data memories after completing an interrupt routine. The processor may also include a program counter (PC) for indicating an address of a next instruction to be executed by the processor, a processor status word (PSW) for indicating a status of the processor, and a user stack pointer (USP) for indicating an address of a bank storing values of the program counter.

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Ohmiya, Japan

Nobuhiro Takiguchi