Vintage Mac 2020 fixes

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, but do let me know if you encounter any problems.

System 7.1 to Mac OS 8.6

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, just drag the patch to the System Folder and restart the computer.

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. The Alarm Clock desk accessory also uses the new APIs.

Version 1.1 of this patch, new Oct 2023, has some improved checks before loading the patch, including calling the ValidDate function to see if it needs to be patched. This prevents the patch from loading when it isn't needed (System 6.0.7/6.0.8), or if the system or ROM itself has been patched. For version 1.1 it is just the loading code that has changed, the patch that is installed in RAM has not changed from version 1.0.

Click here to download 2020Patch 1.1 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 and beyond.

System 6.0-6.0.8, 7.0, 7.0.1

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, and the Alarm Clock desk accessory, to allow dates up to 2040. The System 6 patchers have been revised Oct 2023 to patch more versions, and actually be able to patch on System 6, rather than needing System 7 to run.

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 Alarm Clock 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 to 6.0.8 StuffIt archive - 26K, MacBinary archive - 52K

Click here to download General Z1-3.3.4 patch for System Z-6.0.8L StuffIt archive - 26K, MacBinary archive - 52K

I have yet to take a look at any older system software versions, but I hope to do so soon.

Mac OS 9

Mac OS 9 does not appear to be affected, the Date & Time control panel works up to 2040.


Last modified 2 November 2023. Copyright 2020-2023 Glenn Anderson.