For decades, hardware-centric federated compute architectures dominated both military and commercial aircraft systems, where capabilities were loosely networked together with a quite simple connectivity scheme. The automotive industry had the same architecture where the supply chain delivered components with pure mechanical, and sometimes, simple electro-mechanical capabilities. These were decades when the volume of software on aircraft (and automobiles) was small.
As aircraft designs advanced, the use of software increased, as did the demand for on-board computer systems. Each of these federated systems, usually delivered by different suppliers, typically included an enclosure, redundant power supplies, redundant compute systems with RTOSs, board support packages (BSPs), network/connectivity software and finally federated software applications. This is great for maintenance -- one simply swaps out the federated box and replaces it with another. But as the volume of software applications increases on an aircraft, basing things on individual federated systems becomes untenable due to concerns about size, weight, and power, and related costs (SWAP-C), which is a critical design criterion for aircraft.
Federated compute architectures typically include a hardware enclosure, redundant power supplies, redundant compute systems with RTOSs, board support packages (BSPs), network/connectivity software and finally federated software applications. This is great for maintenance -- one simply swaps out the federated box and replaces it with another. But as the volume of software applications increases on an aircraft, basing things on individual federated systems becomes untenable due to SWAP-C concerns.
ARINC 653 addresses these SWAP-C issues. ARINC 653 systems are typically a singular compute platform, supplied with triple redundant processors, power supplies and network connections. Most of the application software on the aircraft is hosted on a time-and-space partitioned environment with other application software (there still may be a few federated systems on the aircraft). This ARINC 653 environment removes the requirements for every software component to have its own heavyweight hardware, RTOS, power and network infrastructure -- only application software is delivered to the aircraft systems integrator.
In modern software-centric aircraft, this IMA architecture can save over one thousand pounds, opening the opportunity to fly further, as well as fly more passengers, cargo, or fuel, thanks to these SWAP-C savings.
For more information, see 1ARINC 653 Avionics Application Software Standard”, published by SAE International, August 2015, https://www.sae.org/standards/content/arinc653p1-4/