Check out the Klaus Schulze clip, i have one of those synths he's showing but the sit up & beg VCS-3, Mine has a Duophonic 'DK-4' keyboard with it. That what he's got is the case version called the Synti AKS... Mine was a re manufactured one i bought, exactly the same but has MIDI built in it, originals didnt obviously as it never existed in the 60's..EMS specially made one to order with built in Keyboard for the band YES, don't know what happend to it
http://www.bbc.co.uk/programmes/b00nf10k