Vintage Macs are now suffering from problems setting the date to 2020 and beyond, often referred to as a Y2K20 Bug. There is an existing solution, bbraun's free SetDate utility, which is functional, but not a familiar way to set the time on a Mac.
You use these patches at your own risk, I accept no responsibility if these patches cause any problems.
The Date & Time control panel on System 7.1 and later is limited to a range of 1920 to 2019 by an operating system function called ToggleDate. I have created an extension that installs a patch that changes that range to 1941 to 2040, drag it to the System Folder.
System 7.1 has both the General Controls control panel and a Date & Time control panel. The General Controls control panel is also using the new APIs, both work with the patch.
Click here to download 2020Patch 1.0 StuffIt archive - 2K, MacBinary archive - 2K
Mac OS 8.5 and 8.6 also have built in support for synchronising to time servers, which will also set the date to 2020.
The General or General Controls control panel actually has an inconsistency between the up/down steppers and text entry. The steppers cycle through the range 1920 to 2019. With text entry, the range is 1921 to 2020, so the date can be set to 2020 by selecting the year and typing the number "20". I have also created patches for the General and General Controls control panels to allow dates up to 2040.
Click here to download General Controls 7.0.1 patch for System 7.0 and 7.0.1 StuffIt archive - 26K, MacBinary archive - 50K
Click here to download General 3.3.4 patch for System 6.0.8 StuffIt archive - 26K, MacBinary archive - 50K
I have yet to take a look at any older system software versions, but I hope to do so soon.
Mac OS 9 does not appear to be affected, the Date & Time control panel works up to 2040.
Last modified 28 January 2020. Copyright 2020 Glenn Anderson.