Superboard Colour RGB and composite interface

[Steve Gray]

Canada is NTSC. In theory RGB will always be much better than composite. Yes, Don's book is quite interesting. I have a real paper version.

The MC1377 will work, but there may also be some newer chips that need less support components (like inside newer video game consoles... sony?).

Looking at the 540B-1 schematics again. It's been a while. Page one just hits you with a wall of gates that makes my head ache

Right, I don't think getting RGB colour will be too difficult with 540B. It should mostly be a matter of tapping into the corresponding lines.

Once we verify a design we can try to adapt it then.

Steve

[waltermixxx]

from this site: http://www.cpcwiki.eu/index.php/LCD_And ... V_Solution

MP2_Schematic_1.PNG (69.83 KiB) Viewed 14141 times

[MK14HAK]

My 540B-1 has RGB colour! OMG I've been colour blind since I got it a couple of years back. I had noticed it had a crystal and some chips missing and assumed it was mono. It normally sits track side up on my rig and I don't pay much attention to it.This weekend I flipped it over and compared it to the schematics. All the RGB support is there! apart from colour RAM and a buffer and I noticed 1 chip with a leg out of bed.There are some wiring mods to investigate also. So out to the garage for a rummage around and I have uncovered a CBM 1084S-D and a Taxan 12" KS+12+R102S-AX (analog and digital RGB) Vague memories of using the Taxan on A2e back in the 80's but they have not been powered up since. (Will keep a look out for an LCD with a SCART RGB also)
So hopefully I'll have C4 RGB colour in a few days and add PAL composite.

( AD724 looks to require less components )

Just 600RevD to add colour to for me now.The 630 GAL attempt may to wait for retirement.

100*75 *1.6mm PCB 6 days in NZ is $75. Anyone recommend a good China alternative ?

[Steve Gray]

NIce! I now have Walter's 600D board and am going to start breadboarding my circuit. Assuming it works on the 600D I'll see if I can get it working on the 540B.

The AD724 seems to only be available in surface mount. Do you know of a source in DIP package?

Sony or Yamaha also have some RGB to composite like the CXA1645 as used in the MSX machines.

Steve

[MK14HAK]

I think SOIC is just a matter of getting your feet wet. Maybe a bit of practice on a scratch pcb. Lots of tutorials out there.
https://www.youtube.com/watch?v=hoLf8gvvXXU
I haven't done any yet but keen to give it a go. Shame there are not CPLD's in more friendlier hobbyist packages though.
Good luck with the breadboard, look forward to results.

[waltermixxx]

There are little carrier boards that have dip pins, I used one of these chips with an Amiga RGB to Svideo. Very easy circuit.

[Steve Gray]

Breadboarding has started. Well, actually I've finished wiring up a version with hard-coded settings (no dip switch or resistors) and with RGBI+S. Now I have to get a monitor hooked up... more pics to come.

600D-colour-breadboard.jpg (340.34 KiB) Viewed 14114 times

Steve

[Steve Gray]

Well, I've finally connected the monitor, and done some experimenting... Colour is working!... sorta.
I'm still learning how the signals on the U75 connector work but here are proof of concept pics:

I needed to invert the CSYNC signal for my SCART connection. I added some variable resistors on the RGBI lines and the CSYNC line. Colour does not seem consistant from top to bottom. Also, writing to colour ram is not working properly. Anyway, I'll keep at it...

Steve

[Jeff]

Wow!!

[waltermixxx]

Yup I was kinda speechless as well. Great work Steve, please keep it up.
I’m looking to start wiring up mine.

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