These informations were gathered through my own experience, from watches I actually had in hands. They reflect what I observed and are not the absolute truth. Page updated Dec. 6th, 2021 : 6208 movement added.
Text & Pictures : D. Broglin – Watch & Vintage
The Seikomatic range has been introduced at the beginning of the 60’s. It was the upper range of the production of automatic watches by Seiko at that time. As their name means it, all Seikomatic were fitted with automatic movements. They all had at least a stainless steel or gold plated case (so no chromed case). A 18k gold case was available on most models until 1964 (Slimdate, Weekdater). These watches are really rare. The range was also available for women, it was called Seikomatic Lady.
The early years
The first models were time-only watches, based on the Seikosha 603 calibre and date only watches (Seikomatic Self Dater and Slimdate), based on the Seikosha 394. The famous “Weekdater”, with day and date display was introduced in 1963 with the Seikosha 400 calibre. These first couple of years, the name Seikomatic was treated like a brand. The Seiko logo wasn’t present on the dials (see pictures below).
The range has been then (ca 1965) splitted in sub ranges : Seikomatic (62xx movements), Seikomatic-R (83xx movements), Seikomatic-P (51xx movements) and the name Weekdater disappeared. We can link the Seiko Business & Business-A models to the Seikomatic range, they used the 6206 & 8346 calibres and are similar with the Seikomatic & Seikomatic-R.
From 1964 on, the reference at the back follows the generic Seiko rule : Calibre ID – Case ID (ex : 8305-8000). The same calibre/case combination can have different dials (slightly different writings for ex), different hour markers, different hands and different inner and outer bezels (regular, fluted). Before (and at the beginning of) 1964, the reference on the caseback refers to the case and follows this scheme : JXXXXX (for example J14001).
From 1961 to 1968, Seiko produced a limited number of Sportsmatic models, much less than Sportsmatic models for example. We can sum up the production like this :
Seikomatic “time-only”, Seikosha 603 and Seiko 6201 calibres
Seikomatic Self Dater & Slimdate, cal. 394 & 8305
Seikomatic Weekdater, cal Seikosha 400, Seiko 6206, 6208 and 6218 from 1963 to 1965
Seikomatic, cal 6206, 6218, 6245 & 6246
Seikomatic-R, cal. 8305, 8306, 8346 from 1965 to 1968
Seikomatic-P, cal 5106
Seiko Business & Business-A, cal 6206 & 8346
Special models, successors
There were some rare models, including the sought after Seikomatic Silverwave, with a water resitant case, a screwed down crown and an inner rotating bezel. The 6245 and 6246 Seikomatic had the “chronometer” qualification, I think it was the first Seiko to have it.
In 1968, the Seiko Lord Matic (LM) range replaces the Seikomatic range, with the freshly developed 56xx movement, which will equip all mid and high range Seikos (Lord Matic, King Seiko, Grand Seiko). The Seikomatic-P itself will evolve to the Presmatic range, still with the 5106 movement but also with the hi-beat 5146. P and Presmatic refers to the date quickset which is triggered by pressing the crown.