| 摘要 |
PURPOSE:To facilitate generating programs and use an operation instruction which does not directly designate addition/subtraction, by using four generated condition codes for inversion of the sign of the operation result of a decimal operation circuit and conversion to a complement and using them for decision of a branch condition similarly to a binary. CONSTITUTION:The first and second numerical values A and B and respective signs are stored in registers 111 and 112 of a system and the are operated by a decimal operation circuit 12. If carry or borrow is generated as the operation result of the circuit 12, the first condition code C is outputted from an OR circuit 13. Signs of numerical values in registers 111 and 112 are checked by a sign checking circuit 14 to input '0' for positive and '1' for negative to an AND circuit 15, and the second condition code N is outputted from this circuit 15. Condition codes Z And V are outputted from an inverter 17 and an OR circuit 20 respectively. A logic similar to that for binaries is used for decision of branch condition, and generation of the operation program of the circuit 12 is facilitated. |
