IBM 9020

The IBM 9020 refers to IBM System/360-family computers adapted into a multiprocessor system for use by the U.S. FAA for en route Air Traffic Control in its 20 Air Route Traffic Control Centers beginning in the late 1960s. The IBM 9020A, for example, was based on the System 360/50 and the 9020D used 2 out of 3 360/65 processors for flight and radar data processing with 2 out of 3 360/50 processors providing input/output capability.

The 9020As and 9020Ds were in service until 1989 when they were finally replaced by IBM 3083 BX1 mainframes as part of the FAA's HOST upgrade. The 3083s in turn were replaced with IBM 9672 RA4 parallel processing servers during the FAA's Host and Oceanic Computer System Replacement (HOCSR) completed in 1999. At least during the first phase of the upgrade, the 9672's were running the FAA's original assembly language code in System/360 emulation mode. Because of the failure of the FAA's Advanced Automation System (AAS) project, the 9020E display control systems lasted well into the 1990s.

A maximum configuration CCC/DCC complex contained 12 IBM S/360 mainframes. Not all FAA ARTCCs (Air Route Traffic Control Centers), of which there were 20 (plus one in the UK), had the maximum configuration.

A maximum configuration CCC/DCC complex contained 12 IBM S/360 mainframes. Not all FAA ARTCCs (Air Route Traffic Control Centers), of which there were 20 (plus one in the UK), had the maximum configuration. This schematic shows the maximum configuration, with the mainframe boxes highlighted in blue.

One reason for the 1999 upgrade was concern, probably unfounded, that the IBM 3083's microcode would not operate properly in the year 2000.

NATS in the UK had a 9020D system in service running NAS from 1974 to 1989 when it was replaced with a IBM 4381 system.

Sources

• http://www.thegalleryofoldiron.com/9020E.HTM
• An application-oriented multiprocessing system, Part II: Design characteristics of the 9020 system
• Re-engineering software: a case study - air traffic control software - technical
• "IBM FAA 360/65-9020 display". Stanford University Computer History museum. http://infolab.stanford.edu/pub/voy/museum/pictures/display/FAA9020.html. Retrieved June 2, 2010.  pictures of 9020E being recycled