The Y2K20 Bug - Classic Mac OS

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lefevere's picture
Last seen: 3 weeks 1 day 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: 13 hours 17 min ago
Joined: Oct 11 2018 - 22:53
Posts: 60
Oh nice.  Thanks for posting

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

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