On 06/16/2015 01:54 PM, Brent Hilpert wrote:
Once ran across a Honeywell drive (7-track) that had a 'vacuum capstan'. The capstan wheel had a vacuum path through the axle and then transferred the vacuum out to holes around the perimeter. So rather than a pinch roller or rubber frictional surface on the capstan to grip the tape, it was a vacuum holding the tape to the smooth metal surface of the rotating capstan. Or was this common on higher-end vac-column drives?
Two counter-rotating capstans on the CDC 60x, 65x, 66x drives at least. The vacuum/pressure was switched by means of a voice-coil valve. IBM seemed wedded to the pinch-roller model.
I can recall having a discussion about who had the "sloppy write/careful read" versus the "careful write/sloppy read" technology, but don't recall who claimed which. I do remember hours spent with various tapes, developer (e.g. Magna-see) and a loupe looking at patterns on problem tapes.
--Chuck
