[1] Announced in early 1997 as targeting "the next generation of smart appliances", running initially on ARM architecture devices but intended to be easily portable to "other RISC processors" (or even "a range of RISC and CISC processors"[2]), emphasis was made on its quality of service features that would guarantee system resources to critical tasks,[3] as well as its reliability, its sophistication relative to RISC OS (which was described as "too primitive to succeed as a 21st century operating system"), and its small footprint that would "enable Acorn to compete in the semi-embedded systems market".
However, the system's "modular object-oriented" architecture gave it the scalability to potentially be deployed in devices ranging from "multimedia cellular phones" and network computers to desktop workstations and server platforms.
[1] The operating system was to offer an "innovative modular real time kernel",[2] also described as a microkernel[4] with a hardware abstraction layer,[5] having a footprint of only 15 KB.
The kernel itself supported preemptive multitasking, being "multi-threaded and fully pre-emptive", and was portable through extensive high-level language use (an estimated 95% of the code) in conjunction with the hardware abstraction layer.
It was noted that "virtually all Galileo tasks run in user mode", with "complete memory and CPU usage protection" enforced to uphold the quality of service regime.