Historical OS release (IBM PC): When did IBM release the first version of its disk operating system (PC-DOS) version 1.0 for the original IBM PC?

Introduction / Context:
Knowing key milestones in operating-system history helps contextualize how personal computing evolved. IBM’s first disk operating system for the IBM PC, called PC-DOS 1.0 (MS-DOS licensed from Microsoft), marked the beginning of mainstream DOS on x86 desktops.

Given Data / Assumptions:

• The question is about the initial public release of IBM’s DOS for the IBM PC.
• Options cover early 1980s years which map to IBM PC launch history.
• We assume the standard timeline used in computing history references.

Concept / Approach:

The original IBM PC (Model 5150) and its disk operating system arrived together. Identifying the PC launch year pinpoints the DOS 1.0 introduction, since PC-DOS 1.0 shipped with early machines and with the first compatible software ecosystem.

Step-by-Step Solution:

Verification / Alternative check:

Contemporary IBM and trade-press records place both the IBM PC debut and bundled PC-DOS 1.0 in 1981. Subsequent versions, such as DOS 1.1 and 2.0, were released later in 1982–1983, which supports 1981 as the first edition.

Why Other Options Are Wrong:

• 1982 and 1983: correspond to later DOS updates (e.g., 1.1 and 2.0), not the first DOS 1.0 release.
• 1984: aligns with later DOS and PC families (e.g., AT era), not the original PC-DOS 1.0.
• None of the above: unnecessary because 1981 is correct.

Common Pitfalls:

Confusing IBM’s PC-DOS numbering with MS-DOS release numbers; assuming the first mass-market MS-DOS appeared later with the IBM PC/AT (actually introduced in 1984). The inaugural DOS paired directly with the 1981 IBM PC.

Final Answer:

1981