Originally Posted by
chevvron
The 9020 was nothing really special, just 6 x IBM 360s linked together, however it coped - just.
Whilst the 9020 was indeed based on IBM S/360 technology it was rather more than "just six 360s". The 9020 was being designed for the FAA well before the new S/360 line was announced. In fact, this was a major stumbling block (overcome) as the FAA contract specified "off-the-shelf" hardware.
The 9020 CPUs were
based on what was to become the S/360 commercial product line but they incorporated many unique hardware features to facilitate their intended use as an ATC system. These included multiprocessing (a simplified version later added to some ‘standard’ processors), address translation, and specific ATC instructions.
When the UK 9020 was retired in 1989 it was coping very well. Capacity limitations were on the horizon, which is the main reason it was replaced, but not yet causing delays. The hardware was still reliable, though maintainability was becoming difficult. It was a source of pride to the engineers concerned that when it was shut down for the final time the whole system was 100% serviceable.
I am referring to the 9020 system itself, not the NAS software or station power supplies.