| 摘要 |
PURPOSE:To decide the type of an interruption at a high speed by using the contents of a data bus given from outside to enable a microprocessor to give an access to a memory against an external interruption request. CONSTITUTION:A microprocessor 2 reads out the contents of bus registers 7-1 and 7-2 and uses these contents directly as the address information to give an access to a memory 4. In other words, the branching is possible immediately to an interruption destination in response to the type of an interruption request corresponding to the contents of a data bus 9. For instance, '8' is preset to a register 7-1 for upper 4 bits and upper 4 bits of the bus 9 are led to the lower 4 bits of the register 7-1. Furthermore lower 4 bits of the bus 9 are led to upper 4 bits of a register 7-2. Then '0' is preset to lower 4 bits of the register 7-2.
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