A stand-alone program, also known as a freestanding program, is a

computer program A computer program is a sequence or set of instructions in a programming language for a computer to execute. Computer programs are one component of software, which also includes documentation and other intangible components. A computer progra ...

that does not load any external module, library function or program and that is designed to boot with the bootstrap procedure of the target processor – it runs on

bare metal In computer science, bare machine (or bare metal) refers to a computer executing instructions directly on logic hardware without an intervening operating system. Modern operating systems evolved through various stages, from elementary to the pr ...

. In early computers like the

ENIAC ENIAC (; Electronic Numerical Integrator and Computer) was the first programmable, electronic, general-purpose digital computer, completed in 1945. There were other computers that had these features, but the ENIAC had all of them in one pac ...

without the concept of an

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

, standalone programs were the only way to run a computer. Standalone programs are usually written in or compiled to the assembly language for the specific hardware. Later standalone programs typically were provided for utility functions such as

disk formatting Disk formatting is the process of preparing a data storage device such as a hard disk drive, solid-state drive, floppy disk, memory card or USB flash drive for initial use. In some cases, the formatting operation may also create one or more new fi ...

. Also, computers with very limited memory used standalone programs, i.e. most computers until the mid-1950s, and later still

embedded processor An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...

s. Standalone programs are now mainly limited to SoC's or

Microcontroller A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programma ...

s (where battery life, price, and data space are at premiums)
Atmel TinyAVR product page. and

critical system A critical system is a system which must be highly reliable and retain this reliability as it evolves without incurring prohibitive costs. There are four types of critical systems: safety critical, mission critical, business critical and securit ...

s. In extreme cases every possible set of inputs and errors must be tested and thus every potential output known; fully independent eparate physical suppliers and programing teamsyet fully parallel system-state monitoring;
Simultaneous generator control unit 'GCU' failure in 787
Four redundant generator control units in 787 were identical, could fail at same point.
ISO requirements for CE approval performance level 4. or where the

attack surface The attack surface of a software environment is the sum of the different points (for " attack vectors") where an unauthorized user (the "attacker") can try to enter data to or extract data from an environment. Keeping the attack surface as small a ...

must be minimized; an operating system would add unacceptable complexity and uncertainty. (examples, industrial operator safety interrupts, commercial airlines, medical devices, and ballistic missile launch controls, lithium-battery charge controllers in consumer devices

ire hazard and chip cost of approx ten cents Ire or IRE may refer to: Ire * Extreme anger; intense fury * Irē, the Livonian name for Mazirbe, Latvia * A town in Oye, Nigeria * Ire (album), ''Ire'' (album), a 2015 album by the Australian metalcore band Parkway Drive * Ire (Iliad), a town me ...

) Resource limited microcontrollers can also be made more tolerant of varied environmental conditions than the more powerful hardware needed for an operating system; this is possible because the much lower clock frequency, pin spacing, lack of large data buses (e.g. ddr4 ram modules), and limited transistor count allow for wider design margins and thus the potential for more robust electrical and physical properties both in circuit layout and material choices.

References

{{- Legacy systems Computer programming

See also

References