But, what did these develop out of?? Well, with the help of BQ-Watch Museum and our database, we can try to trace the development of these lines:
1. In the mid 20th century Seiko appeared to use a variety of calendar models based on Swiss movements. Some of these were marked as Chronometer as well. They came in a variety of display types & some used pointer-date style + window displays. From our database entry:
From BQ-Watch ...
In 1951, Seiko Suwa produced the following model:
As we can see, there is no "Dater" badging at that stage.
2. In 1953, Suwa had the following style:
which have now been given the designation of "Auto Dator" ... but, I would caution that "Auto" here does NOT mean automatic-wind!! It has been rather authoritatively stated in various Japanese sources that the 1st automatic-wind Seiko came out in the 1955 timeframe [cal. 11A with Power Reserve Indicator] with a Swiss [or Swiss design] movement:
This "Dator" can also be seen in our database @
3. In 1954 the following evolution occured, also from Suwa:
Note that this "Dator" style has been incorporated into the Super family of watches! That was Seiko's "big" model prior to the Marvel.
We have now dispensed with the pointer-date style of calendar display [for Date] and switched over to a window-type display, like in the "Daters" of the '60s.
We now, (likely) for the 1st time, have a watch that uses a badging terminology that is quite close to the "dater" style of the '60s as Seiko replaced the "Auto" with "Self" in the dial badging. However, we still see that the naming is still a little different from the "Dater" terminology used in that later generation since the older spelling is retained ["o" instead of "e"].
BUT, we now see at this stage, the very close antecedent to the "Self Dater" of the '60s!!