"[5][6] A looking back described it as "bare basics .. handled interrupts .. scheduled processes, and provided interprocess communications" without being "all things to all people.
"[7] Another description, rather than focusing on taking away overhead, wrote "IAS (Interactive Application System) was created by adding two things to 11D.
[1]: p.2 The system could be tuned to either leave unused CPU cycles to batch, or to guarantee a minimum level (without taking from Real Time requirements).
"[10]: p.13 An evaluation by TRW's Defense and Space Systems Group for Tactical Operations Analysis Support Facility at Langley AFB VA highlighted the "IAS heuristic timesharing scheduler" and "subtasking support at the Kernel Executive level via the SPAWN system directive.
"[10]: p.28 The heuristic timesharing scheduler tracks "history of performance and degree of interaction.