"Koz" wrote in message
...

However, is there really that much difference between holes punched in a
card telling a machine where to go and profiled cams telling a machine
where to go? I guess one may have a mechanical linkage where the other
may have an electrical linkage. Either way, they are both effectively
numerical control.

Cams give you automatic control, but not numerical positioning instructions.
They're a kind of proportional control, as opposed to numerical control.

The big difference, and the line of demarcation, is between control systems
that are numerically programmable, or programmable with a discrete set of
symbols or numbers, and those that require making a proportional-control
pattern or model.

--
Ed Huntress
(remove "3" from email address for email reply)