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The Unix Time-Sharing System: Early Development by Ken Thompson and Dennis Ritchie
Key points
- Ken Thompson initiated Unix development after AT&T left the Multics project.
- Thompson focused on optimizing disk throughput on a GE-645 computer.
- He later used a PDP-7 to continue development and complete the operating system.
- Dennis Ritchie joined Thompson in the development of Unix.
Origins of Unix
The Unix Time-Sharing System originated from Ken Thompson's dissatisfaction with available computer facilities after AT&T withdrew from the Multics operating system project. Thompson, then at Bell Labs, pursued self-directed research, which was common practice at the institution.
Initial Development and Disk Optimization
Thompson gained access to an idle GE-645 computer, previously used for Multics work, and focused on optimizing disk throughput. His goal was to improve drum seeking algorithms and enable simultaneous overlapped reads, a challenge not adequately addressed by existing systems.
After losing access to the GE-645, Thompson found a little-used PDP-7. He utilized this machine to continue his research on disk layout and accessing schemes, realizing he was close to completing a full operating system.
System Completion and Collaboration
Thompson estimated he needed approximately three weeks to finish the operating system on the PDP-7, which already included a file system, disk driver, and I/O peripherals. His personal effort was successful enough to attract the interest of Dennis Ritchie and other colleagues, leading to their collaboration on Unix.
Historical Significance
The foundational work by Ken Thompson and Dennis Ritchie on Unix laid the groundwork for subsequent operating systems, including Linux. Linus Torvalds has acknowledged the design influence of Kernighan, Ritchie, and Thompson on Linux.
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Reporting from
This article details the early history of the Unix Time-Sharing System, focusing on Ken Thompson's initial motivation to create a more hospitable computing environment after AT&T withdrew from the Multics project. It highlights Thompson's work on disk throughput optimization and his subsequent use of a PDP-7 to develop the foundational elements of Unix.