Suwa Seikosha produced the 5600 series of high-end automatic watch movements for Seiko in the 1960's and 1970's.

This line was used in various Lord Matic, King Seiko, and Grand Seiko models from 1968 through 1976. It appeared first in the 1968 Lord Marvel, next in 1969 in the King Seiko 56KS, and finally in 1970 in the Grand Seiko 56GS. It was also used in two other Seiko models - the Seiko Duotime and Seiko Chronometer.

Unlike previous Grand Seiko movements, production of Calibre 5600 was highly automated. This made the movements cheaper and helps to this day since parts are more plentiful. But the speed of the movement was reduced from “Hi-Beat” 36,000 A/h of its predecessors.

The 5600 family was introduced in 1968 for the Lord Matic and first appeared in King Seiko guise the following year. This was the first Suwa movement used in the Daini King Seiko line.

The 5600 family was produced in four grades and with three complication sets

• Grades
  • Lord Matic - 560x - 20-25 jewels, unregulated, 21,600 A/h
  • King Seiko - 562xA - 25 jewels, unregulated, 28,800 A/h
  • King Seiko Regulated - 562xB - 25 jewels, regulated, 28,800 A/h
  • Grand Seiko - 564x - 25 jewels, regulated, 28,800 A/h
• Complications
  • 56×1 - No complications
  • 56×5 - Date only
  • 56×6 - Day and date
  • 5619 - Dual time (Lord Matic and Duotime only)

• Seiko 6800 - Another ultra-thin movement from that era

• Lord Matic
  • 1968-1978 - 5601A
  • 1968-1971 - 5605A
  • 1968-1978 - 5606A
  • 5262 (Lord Matic De Luxe)
• King Seiko 56KS
  • 1969-1973 - 5621A/5621B
  • 1968-1974 - 5625A/5625B
  • 1968-1973 - 5626A/5626B
• Seiko Chronometer
  • 1969-1973 - 5625B
  • 1969-1974 - 5626B
• Grand Seiko 56GS
  • 1971-1972 - 5641A
  • 1970-1973 - 5645A
  • 1970-1974 - 5646A
• Seiko Duotime
  • 1972-1974 - 5619A

• Qualified for Time Travel: SEIKO 4S36 GMT Retrograde SARN001
• Private Collection - Grand & King Seikos