| 摘要 |
PURPOSE:To prevent runaway of a program, to improve an RAS function (reliability, usability and maintenance property), and also to reduce the number of steps of a microprogram, by providing a stack pointer control circuit. CONSTITUTION:A micro-instruction stored in a control storage device 1 is led to a switching circuit 11 and a decoding circuit 12 through a micro-instruction register 2. The circuit 12 decodes a part of a signal from the register 2, and outputs it to the circuit 11, an address stack 4 and a stack pointer control circuit 5. The circuit 5 inputs an output of the circuit 12 and a signal 201 from an operation executing device, and executes various controls. That is to say, it increases or decreases an address pointer to the stack 4, clears the stack pointer, and generates machine error signal when overflow or underflow of the stack pointer is detected, and executes a control such as prevention of runaway, etc. In this way, an RAS function (reliability, usability and maintenance property) is improved, and the number of steps of a program can be reduced. |
