Re: CNC scripting stuff....

I think APT was probably written and run on nearly every type of
computer system up through to the 80's and perhaps even into the
90's. Obviously, pre-80's computers were much different than what we
see today.

NC machines used to be referred to as tape machines. They used
paper (or mylar) tape with punched holes in it. If you have ever
seen teletype machines - same thing.

The machine would read the line of code off of the paper tape,
execute it, then read the next line, execute it and so on.
Generally there was some buffering of the data so the machine ran
pretty smooth, nothing like what we see today though.

Also, those machines (NC) didn't have CRTs like we have today.
Rather you had a series of 7 segment LEDs that would display one
word of the program at a time - this feature was actually rare on
early NC machines. Basic practice was to "Punch out a paper tape"
and at the same time, using a teletype (or teletype type of machine)
print out the program listing - without the printout, it was a
nightmare.

The transitional controls like the FANUC 5 series(General numeric
2000, and 3000 series) had memeory and you could load the program
into memory. But still, we didn't have the CRTs till the FANUC 3
and 6 series controls came out in the late 70s.

Some of the wording used on CNC machines today still relate to the
NC days. For example "Punch" is used frequently on newer controls
to output a CNC program to a computer. If you look through some of
the newer CNC control manuals, they still show diagrams of what a
paper tape punch code looks like in EIA.

Chris







--- In CAD_CAM_EDM_DRO@yahoogroups.com, Alex Holden <alex@l...>
wrote:

> On 17 May 2005, at 7:08 pm, lcdpublishing wrote:
> > They were not CNC machines, they were NC machines, slight

difference

> > there. The first NC machine appeared at an IMTS show in Chicago
> > right around 1955.
>
> Presumably they ran APT code through a compiler on a mainframe to
> generate a set of commands for a NC machine then? How were the

early

> NC machines controlled and how did they get the machining
> instructions from the computer to the machine?
>
> --
> ------------ Alex Holden - http://www.alexholden.net/ ------------
> If it doesn't work, you're not hitting it with a big enough hammer