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Fadal 1420-1 Video Card Reverse Engineering and Schematic

This article originally appeared in My little (home) shop thread on Practical Machinist.

I finished my reverse engineered schematic of the Fadal 1420-1 video board. I’d estimate I have 20-25 hours into the schematic at this point.

The schematic, and observation of the control display, lead to some interesting observations about the original design.

It’s widely told that Adrian de Caussin is the one who designed the control hardware, unfortunately he passed away some time ago (a reference from 1996 indicates he’d passed by then), so this public accounting may be the only hardware level details known outside of the de Caussin family.

I did reach out to David de Caussin the younger to try and learn details about the original control development, because at this point they are considered vintage computer systems. Unfortunately I didn’t receive a reply from him, so I had to go at it myself.

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Fadal Chargen ROM Reverse Engineering

This article originally appeared in My little (home) shop thread on Practical Machinist.

Fadal Chargen ROM

That’s the contents of the character generator ROM on the Fadal video card. I used a Parallax Propeller development board to make a breadboard EPROM reader.

I’m interested in making a video card that will plug in place of the Fadal card and output a video format of my choosing.

Specifically I’m talking about using a Parallax Propeller microcontroller to generate a VGA signal. The picture is actually the Propeller outputting the ROM data to a VGA monitor.

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Fadal CNC Reverse Engineering

This article originally appeared in My little (home) shop thread on Practical Machinist.

Just to be clear, the control and electronics work fine on my Fadal at present, it was the iron that needed major help.

The process of reverse engineering the control started with researching the history of the Fadal control. On the VMC Electric website they give a few pieces of information about the process of creating the control.

They said they used an Imsai 8080 to develop the NC executive. If you read closely you’ll see they used the NC software to process G-code into NC tapes for their other machines. This specifically includes applying cutter radius compensation and other stuff that old NC systems couldn’t do.

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