Interprocessor audits divided into partitions that run on a single processor. Interprocessor audit execution controled by CP, which receives completetion reports from each partition. About 70 application audits. Current software development methodologies incapable of producing fault-free programs. Operator mistakes introduce incorrect data into system.
Hardware faults cause data mutilation.
Outage - Failure effecting significant number of jobs Fault tolerant systems prevent errors from becoming failures and failures from becoming outages. No more than 2 calls out of 10,000 mishandled. Tolerable response times range from milli-seconds to seconds. Interrupts for timing and hardware exceptions.