iAPX 432 Interface Processor Architecture Reference Manual
The I-bit segment bound subfield indicates whether or not the associated fault was caused by a segment bounds violation. A value of zero indicates that the fault was not caused by a segment bounds violation. A value of one indicates that the fault was caused by a segment bounds violation.
The I-bit menory overflaY subfield indicates whether or not the associated fault was caused by a memory overflow. A memory overflow occurs when the sum of the physical base address in bytes of a segment being accessed plus the byte displacement to the operand being accessed exceeds 16,777,215 (i.e. 2**24-1).A value of zero irrlicates that the fault was not caused by a memory overflow. A value of one indicates that the fault was caused by a mennry over flaY.
The I-bit access direction subfield indicates whether or not the associated fault was caused bv an access direction error. An access direction error occurs when the transfer direction subfield of the corresponding map entry state irrlicates that the requested access di+ection (either read or write) is invalid. A value of zero irrlicates that the fault was not caused by an access direction error. A value of one indicates that the fault was caused by an access direction error.
The I-bit post termination subfield indicates whether or not the associated fault was caused by a post termination error. A post termination error occurs when an access is attempted after a transfer via the associated map entry has terminated. A value of zero irrlicates that the fault was not caused by a post termination error. A value of one indicates that the fault was caused by a post termination error.
The I-bit partial block overflaY subfield irrlicates whether or not the associated fault was caused by a partial block overflCM. A partial block overflaY occurs when there is one byte left to be transfered in a block arrl a double-byte request is made. A value of zero indicates that the fault was not caused by a partial block overflow. A value of one indicates that the fault was caused by a partial block overflCM.
The I-bit block overflaY subfield indicates whether or not the associated fault was caused by a block overflow. A block overflow occurs when the block count is zero, the Peripheral Subsystem attempts an access, am the map entry state has not yet been updated. A value of zero indicates that the fault was not caused by a block overflow. A value of one irrlicates that the fault was caused by a block. over flaY •
