| 摘要 |
PURPOSE:To transmit an error signal before memory access is executed when the address of the memory access is coincident with the address of a protecting area by providing a means setting optionally the address of the protecting area of the memory in a firmware computer and a means comparing an address accessing the memory and an address designating this protecting area. CONSTITUTION:A memory address register 1 stores an address accessing a memory 3. The protecting table 2 comprising registers stores an address set optionally by a control storage area 3-1 in which control information in the memory 3 to be protected in advance is stored. The memory 3 is divided into the control storage area 3-1 in which the control information is stored and a working area 3-2 in which a working data is stored. Coincidence/dissidence between each bit of the memory address register 1 and each bit of the protecting table 2 is detected by AND circuits 5-7. When bits coincident with each other exist, an OR circuit 8 is set and its output is fed to an error processing section 4 as an error signal. |
