Historical clue formulations

• Operating system developed at Bell Labs — 2026-03-12
• Computer operating system developed by Bell Labs — 2026-02-16
• Windows alternative — 2026-01-09
• Operating system developed by Bell Labs — 2025-02-13
• Operating system developed at Bell Labs — 2024-09-25
• What macOS is based on — 2024-04-10
• System for servers — 2023-04-28
• Common operating system for supercomputers, once — 2022-10-06
• Bell Labs development of the 1970s — 2021-11-06
• See 55-Down — 2021-09-28
• Operating system developed at Bell Labs — 2021-06-14
• Operating system from Bell Labs — 2020-11-26
• Early operating system — 2019-12-05
• Pioneering computer operating system — 2019-05-22
• Operating system developed at Bell Labs — 2018-10-14
• Certain operating system — 2018-10-03
• Operating system since the early '70s — 2018-08-12
• Operating system developed at Bell Labs — 2018-02-01
• Linux forerunner — 2017-10-03
• System used by servers — 2017-08-18
• Operating system with many clones — 2017-02-22
• System developed by Bell Labs — 2017-01-28
• Pioneering computer operating system — 2016-08-17
• Operating system developed at Bell Labs — 2016-04-24
• Operating system used since the 1970s — 2015-12-08
• Bell Labs operating system — 2013-11-13
• Bell Labs system — 2013-10-20
• It has "batch" and "patch" commands — 2013-09-07
• Longtime computer operating system — 2013-07-17
• Operating system since 1969 — 2013-03-05
• MS-DOS alternative — 2012-11-20
• Operating system since 1969 — 2012-10-02
• Computer operating system developed at Bell Labs — 2011-01-17
• Operating system developed at Bell Labs — 2008-09-04
• Windows alternative — 2006-08-30
• Popular computer operating system — 2006-08-15
• Popular computer operating system — 2005-10-26
• Alternative to Windows — 2005-07-28
• System for servers — 2005-01-22
• Windows alternative — 2004-08-29
• Operating system on many Internet servers — 2004-07-20
• Computer operating system developed by Bell Labs — 2001-04-24