I've started (very early days) indexing sales images with case back info for these digital watches. With only 65 total digital world times indexed so far, it looks like this:
- M158: April 1977 - January 1979
- A358: April 1979 - February 1980
- A239: July 1979 - April 1980
- A708: May 1984 - May 1988
- A718: February 1984 - June 1984
You can browse the data here:
A summary of SEIKO digital world time watches by model - and a work in progress
This will get built out like the mechanical watches eventually.
I have an A239-502A in the mail, and recently added the this one to my collection (the A718 at right):
I've also finally put up a first revision/post on the M158-500X:
All about the 1st series of digital LCD world time watch from SEIKO, produced in 1977
I've also put up the ad/catalog scans that I could find:
A small collection of ad and catalog scans of the SEIKO World Time M158-500X
Those are my first write-ups on these digital world times... If you spot anything incorrect, please let me know. More soon...