In computing, preemption is the act performed by an external scheduler — without assistance or cooperation from the task — of temporarily interrupting an executing task, with the intention of resuming it at a later time. This preemptive scheduler usually runs in the most privileged protection ring, meaning that interruption and then resumption are considered highly secure actions. Such changes to the currently executing task of a processor are known as context switching.
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Preemptive multitasking in the context of Commodore International
Commodore International Corporation (CI), also known as Commodore International Limited, was a home computer and electronics manufacturer with its head office in The Bahamas and its executive office in the United States founded in 1976 by Jack Tramiel and Irving Gould. It was the successor company to Commodore Business Machines (Canada) Ltd., established in 1958 by Tramiel and Manfred Kapp. Commodore International, along with its U.S. subsidiary Commodore Business Machines, Inc. (CBM), was a significant participant in the development of the home computer industry, and at one point in the 1980s was the world's largest in the industry.
The company released its first home computer, the Commodore PET, in 1977; it was followed by the VIC-20, the first ever computer to reach one million units of sales. In 1982, the company developed and marketed the world's best selling computer, the Commodore 64; its success made Commodore one of the world's largest personal computer manufacturers, with sales peaking in the last quarter of 1983 at $49 million (equivalent to $129 million in 2024). However an internal struggle led to co-founder Tramiel quitting, then rivaling Commodore under Atari Corporation joined by a number of other employees. Commodore in 1985 launched the Amiga 1000 personal computer — running on AmigaOS featuring a full color graphical interface and preemptive multitasking — which would initially become a popular platform for computer games and creative software. The company did particularly well in European markets; in West Germany, Commodore machines were ubiquitous as of 1989.
View the full Wikipedia page for Commodore InternationalPreemptive multitasking in the context of Amiga 1000
The Amiga 1000, also known as the A1000, is the first personal computer released by Commodore International in the Amiga line. It combines the 16/32-bit Motorola 68000 CPU which was powerful by 1985 standards with one of the most advanced graphics and sound systems in its class. It runs a preemptive multitasking operating system that fits into 256 KB of read-only memory and was shipped with 256 KB of RAM. The primary memory can be expanded internally with a manufacturer-supplied 256 KB module for a total of 512 KB of RAM. Using the external slot the primary memory can be expanded up to 8.5 MB.
View the full Wikipedia page for Amiga 1000Preemptive multitasking in the context of AmigaOS
AmigaOS is a family of proprietary native operating systems of the Amiga and AmigaOne personal computers. It was developed first by Commodore International and introduced with the launch of the first Amiga, the Amiga 1000, in 1985. Early versions of AmigaOS required the Motorola 68000 series of 16-bit and 32-bit microprocessors. Later versions, after Commodore's demise, were developed by Haage & Partner (AmigaOS 3.5 and 3.9) and then Hyperion Entertainment (AmigaOS 4.0-4.1). A PowerPC microprocessor is required for the most recent AmigaOS 4-release.
AmigaOS is a single-user operating system based on a preemptive multitasking kernel, called Exec. It includes an abstraction of the Amiga's hardware, a disk operating system called AmigaDOS, a windowing system API called Intuition, and a desktop environment and file manager called Workbench.
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