Emulating a smart CRT display unit - ideas?

Chuck Guzis cclist at sydex.com
Tue Aug 24 17:33:33 CDT 2010

On 24 Aug 2010 at 20:20, Arno Kletzander wrote:

> some of you will perhaps remember me being stuck with a problem
> regarding a Fujitsu FANUC "mate TG" CNC controller (rebadged as
> "Siemens Sinumerik"), of which I have the main unit but not the
> monitor. Thanks to a very nice guy living nearby, I was provided with
> some new information about the interface, which is rather uncommon in
> itself. I had already guessed that there is a significant amount of
> smarts in the monitor; the newly acquired documentation confirms this.
> The silicon brain (CRT controller) of the thing is called LSI HD46505.

I beleive the HD46505 is basically a clone of the Motorola 6845 CRTC, 
so there's not a lot of information there.

> Does this ring any bells with anyone? Are there similar monitors out
> there that might be converted with little effort? Otherwise, the
> registers and instructions are described in enough detail so that
> making a replacement or some sort of emulation at least seems
> possible. What sort of hard- and/or software would one be looking at
> to accomplish this? 

Although I've seen disks from various Fanuc machines, I've never been 
up close to the actual controller that you describe.  I suspect that 
one might be able to cobble up an interface to a commodity PC, 

> I have some hazy memory of seeing a demonstration of a Pong game
> programmed in LabView(!) running on an FPGA based device which would
> directly generate VGA output, but that was a very expensive unit. For
> now I'm just looking for a cheap and simple way to give me some idea
> of what, if anything, the controller is trying to display.

If you want a dedicated unit, an FPGA might still be your best bet, 
if you have the skills (VHDL or Verilog).  Alternatively, many faster 
microcontrollers can directly generate video using nothing but 

But you're going to need a fair level of detail on what actually goes 
on over those 12 lines before you can get something going.  To that 
end, why not post a note to this guy:


Who seems to have a lot of information on his hands?

Best of luck,

More information about the cctalk mailing list