The Y2K20 Bug - Classic Mac OS

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lefevere's picture
Last seen: 3 months 2 weeks ago
Joined: Apr 13 2004 - 20:40
Posts: 59
The Y2K20 Bug - Classic Mac OS

Date & Time Control Panel in Mac OS 8 (released in 1997) will only let you set a Mac’s date to a range between January 1, 1920 and December 31, 2019

There is a utility that will allow you to set the date and time on your Classic Mac all the way up until the last second: SetDate


Simply type in the date and time (in military format)

The Looming Y2K20 Bug


Download SetDate (17KB)

Allows setting the date/time through 2042. The stock System 7 Date & Time control panel has problems with current dates. This allows manually setting the date & time through 2042 when deeper problems arise

Classic MacOS Software


Military Date Time Group

In US military messages and communications the format is DD HHMMZ MON YY.

Although occasionally seen with spaces, it can also be written as a single string of characters.

Example 1: 091630Z JUL 11 represents (Jul) 09 16:30 Jul 2011 (UTC).

Example 2: 141608Z Dec 19 represents (Dec) 14 16:08, Dec 2019 (UTC)

Military Date Time Group


tested on SE/30

mac system 7.0 no problem since only dozens (tens) and units are displayed


tested on IIci

mac system 7.1 > patch


mac os 8 > patch

Lee Adamson's picture
Last seen: 5 months 1 day ago
Joined: Oct 11 2018 - 22:53
Posts: 92
Oh nice.  Thanks for posting

Oh nice.  Thanks for posting this.  I was getting pretty discombobulated living in 1920, haha.

Last seen: 1 year 2 months ago
Joined: Feb 17 2020 - 17:28
Posts: 2
SetDate Issue

Question:  Once I download the SetDate fix, what do I do with it.  Do I place the fix in my Extentions folder, System Folder, Control Panels?  Any suggestions would be welcomed.  Thanks.

Last seen: 1 year 2 months ago
Joined: Feb 17 2020 - 17:28
Posts: 2
I figured it out.

So, what i figured out on how to use the 2020 fix might seem simple to many on this forum, however, it took me some time to figure out and here is the answer for anyone running into the same issues I did.


First, figure out how to download the program from the internet to your older Mac.  I am using a Quadra.  A 3.5 floppy formatted disk from the Quadra was not working, so I formated a 3.5 disk on a PowerPC Mac.  This formatted disk worked.  I paid for a computer person to download the file to the 3.5 disk.  I placed the PowerPC Mac disk into the PowerPC and transfered the download to my server and then to my Quadra.  I do not know if this specific step was necessary.


The files are a document file with cpt. and hqx. extentions.  These files will not do anything unless and until you "unpack" them by using a program such as Stuffit.  Once I "expanded" the file, (all you need to do is one of them) then the document becomes a Control Panel icon that can be placed in your Control Panel.


Restart your Mac and you should be able to open the SetDate and set the date.


Again, this might be very basic for most, but for me it took some time.


Good luck.

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