Control Data 841 disk drive's 3-phase power supply resurrection
p.gebhardt at ymail.com
Sun Feb 18 12:46:49 CST 2018
>The claim about the "only CDC disk drive with hydraulic positioner" is
>false. Starting with the Bryant 6603, I believe that the 808 and very
>rare 821 also used hydraulics. Voice-coil positioners started to be
>used with the 844 drives. I don't recall what the 854 used, as it
>wasn't very common on big CDC iron.
Chuck, thanks a lot for your reply and for these insights! I indeed wasn't aware that within CDC, the 808 and 821 worked-with hydraulics, too. I will update the description on the web accordingly!The 85x drives don't use a hydraulic positioner. To my understanding, they used a solenoid and a carriage assembly that is controlled by a photo-cell, -transistor and a timing wheel with slots.
All the best,Pierre
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