JPS56143063A - Common storage protection system - Google Patents

Abstract

PURPOSE:To simplify the common memory protection management, by providing a plurality of interface IF devices connected to the common memory device with the memory protection lock memory individually and managing the memory independently. CONSTITUTION:The memory device 1 is commonly used for computers 3a-3c via IF devices 2a-2c. The computer 3 sets the write-in address to the address register 21 of the IF device 2, write-in data to the data register 22, and protection key at data write-in to the protection key register 23. The protection lock is read out from the protection lock memory 26 according to the content of the register 21, and the content of the register 23 is compared with it at the comparison circuit 25. As a result of comparison, if it is judged as write-in possible, the access to the device 1 is requested, and when the use of bus is permitted with the bus controller 4, data is written in the address set in the memory 15. If judged as write-in impossible the access request to the device 1 is inhibited, the write-in impossible signal is fed to the memory protection detecting circuit 24 and error is reported to the computer 3.