Re: [CAD_CAM_EDM_DRO] for John Elson

rschlierbeck wrote:

> John,
>
> I am very much interested in your photoplotter design. Would you be
> willing to share your design details? I have been thinking of
> building a machine like this for a couple of years now and yours'
> looks like exactly what I want to do.

Well, I suppose I might be able to do that. But, the software is quite
complex,
and I don't think I can give that away. Of course, if you could fix the
last thing I
couldn't get working in the program, then I might be able to arrange
that, too.
(The program is in Turbo Pascal for Windows, and needs to program the
motherboard DMA controller with the physical memory address of the
data buffer so the ISA DMA card can transfer the raster line to the
plotter.
I never got this to work. I do have a simpler program that runs in DOS
emulation mode, and VDS (virtual DMA Services - a secret 'driver' in
Windows
95) handles the conversion properly. So, what I have to do is run the
Windows
program which generates a huge disk file, and then use a DOS program to
plot it out to film. Not a huge problem, just a slight irritation.)

Anyway, this machine is QUITE complex, even though I made it as simple
as I could. It also cost a LOT more to make than I expected, and took
almost
10 years to design and build. (Of course, I had to wait for laser
diodes to become
affordable items, too.)

There is also a TI digital phase locked loop IC that may no longer be in
production
in the design. It is a pretty key piece, as it multiplies the 1024
encoder pulses by
20, to generate the pixel clock. This could probably be replaced with
an FPGA
now, but it is just another complication in making a copy of my machine.

Jon