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Real-Time Clock: date and time on the Amiga

AExp can feed the emulated Amiga 500 the MEGA65's own battery-backed clock. Once it is set up, Workbench shows the real date and time, and the files you create carry proper timestamps.

Setup takes a minute. There are also two small surprises worth knowing about: on Kickstart 1.3 the year can come out wrong (stuck at 1978), and the time can be off by an hour. Both have simple fixes, and neither is a fault in AExp. A real Amiga 500 running Kickstart 1.3 behaves exactly the same way.

Setting it up

The Amiga 500 shipped without a clock. It was an add-on that lived on the A501 trapdoor expansion, and Kickstart 1.3 does not read it on its own. So two things need to be in place:

  1. Set the MEGA65's clock. Make sure your MEGA65 clock is set to the correct date and time and that it works. (On some R3 machines you need a hardware fix for the RTC.)
  2. Load the clock at boot. Your Workbench disk needs to run SetClock LOAD early in its s:startup-sequence. Stock Workbench 1.3 disks already do this, so there is usually nothing to add.

Now boot the core, open a Shell, and type date. You should see the current date and time.

Surprise: the year says 1978

If date prints something like this:

Sunday 09-Jul-78 16:48:20

then the day, month, and time are correct, but the year is wrong. It should read 2026.

Why it happens

The Amiga's clock chip stores the year as just two digits, 00 to 99. It never records the century, so the software has to fill that part in. Commodore's intended rule was:

  • 78–99 means 1978–1999
  • 00–77 means 2000–2077

By that rule, 26 becomes 2026. The trouble is the SetClock program on the original Workbench 1.2 and 1.3 disks. It predates the year 2000 and never applies that rule. It reads every two-digit year as 19xx, and because 1926 is earlier than the Amiga's starting point of 1 January 1978, it gives up and falls back to 1978. The day, month, and time are worked out separately, which is why they stay correct while only the year looks wrong.

AExp hands the Amiga the right value the whole time (the digits 2 and 6). The century mix-up happens entirely inside that old SetClock. Commodore released a corrected version back in 1998, and that update is the whole fix.

Fix option A: replace the SetClock file

Swap the old SetClock on your Workbench disk for the corrected one, called SetClock 34.3.

  1. Download it from Olaf Barthel's site: SetClock_v34.3.lha. The page that explains the whole thing is amiga.de/diary/developers/y2k.html.
  2. Unpack the .lha archive. Inside is a single program, SetClock (about 7 KB, dated September 1998).
  3. Copy it into the C: drawer of your Workbench 1.3 disk image, replacing the old one. On a PC or Mac, xdftool from amitools does the job: 
    xdftool workbench-1.3.adf delete c/SetClock
xdftool workbench-1.3.adf write SetClock c/SetClock
    You can also mount the ADF in WinUAE and run copy SetClock c:.
  4. Boot the disk. The SetClock LOAD line already in the startup-sequence takes care of the rest.
  5. Check the result: version c:setclock should report 34.3, and date should now show 2026.

Do not judge the file by its size. An old guide suggests a good SetClock is under 1 KB, but the corrected 34.3 is itself around 7 KB, so size tells you nothing here. Trust version c:setclock.

Fix option B: download a Workbench that already has the fix

If you would rather not edit files by hand, grab a Workbench image that already ships the corrected SetClock. The Internet Archive hosts the full Commodore Workbench collection:

archive.org/details/commodore-amiga-operating-systems-workbench

Look for Workbench 1.3.3, Cloanto Amiga Forever Edition. Cloanto's release includes a Y2K-corrected SetClock, so once you boot it and SetClock LOAD runs, the year is already right. The plain "(Commodore)" 1.3.3 images still carry the original buggy SetClock, so after downloading, confirm with version c:setclock and switch to Option A if it reports an older version.

Workbench 1.3.3 (revision 34.34) is the last release of the 1.3 line, so it is as new as you can go while staying on Kickstart 1.3, which is what AExp runs. Workbench itself is copyrighted software, so download it for a machine you are entitled to use it on.

A few things worth knowing

  • The clock is read-only from the Amiga's side. Set the time on the MEGA65, not with SetClock SAVE inside the Amiga.
  • Even while the year shows 1978, file dates still sort correctly against each other, because AmigaDOS counts days from its 1978 origin. Only the printed year looks off, so demos and everyday work are unaffected.
  • Everything here matches a real Amiga 500 with Kickstart 1.3. The fixes are the same ones the Amiga community has relied on for years.

Further reading

For the full background, these are worth a look: