IBM System/7 Functional Characteristics - All about the IBM 1130 ...

Significant Bits Meaning3 Seek check. One of the following error conditions has occurred duringa seek operation:1. The access mechanism, while moving in the forward direction,attempted to move beyond the innermost cylinder on the disk (thisis sometimes called access overrun).2. The access mechanism, while moving in the reverse direction,reached cylinder 0 before the operation was supposed to end. (Thiscondition will not occur during a recalibrate operation.)3. The access mechanism attempted to move in either the forwardor reverse direction for 1 to 2 seconds.4. A track-crossing pulse was detected at the end of head settlingtime, indicating that the access mechanism moved past the desiredcylinder.The seek-check indicator bit also sets the any-error bit and deviceendbit in the interrupt status word.4 File data check. The check character read from the sector and thecheck character generated while reading either the sector ID or thedata field did not compare equally. The any-error bit (bit 3) and thedevice-end bit (bit 13) are also set in the interrupt status word bythis error condition.ISWEX Normal Position: Bits 5 through 15 assume the following meaning when the plugis connected to the normal position in the disk storage module.5 File sense 1. This is a pluggable line that can be used to monitor conditionsin the disk storage module. The normal position is to monitorthe write unsafe latch.6 File sense 2. This is a pluggable line that can be used to monitorconditions in the disk storage module. The normal position is tomonitor the read/write unsafe latch.7 File sense 3. This is a pluggable line that can be used to monitorconditions in the disk storage module. The normal position is tomonitor the erase unsafe latch.9 Parallel parity check. One of the following conditions has occurred:1. On a write operation, the parity of the word transferred from theprocessor did not compare with the parity generated as the wordwas serialized by the serdes register.2. On a read operation, the parity generated as the word was deserializeddid not compare with the parity of the word when it wastransferred to the processor.10 Check counter error. The contents of the bit count appendage (BCA)counter did not contain the correct value after being reset.11 Write gate check. The write gate line was active when an index markwas detected and no format track operation was in progress.13 Cylinder zero. The access mechanism is located at the cylinder 0position.14 Diagnostic mode. The disk storage module is in the diagnostic modeof operation.15 Write inhibited. The file write switch on the disk storage module is inthe write inhibit position.