Game-Tech.US Posted October 31, 2010 Share Posted October 31, 2010 I have a gemini I want to put the longhorn av mod into, but am unsure of which chip is the TIA for sure or if its trully the same as the 2600 TIA? Quote Link to comment Share on other sites More sharing options...
OldAtarian Posted October 31, 2010 Share Posted October 31, 2010 (edited) Was TIA a general purpose chip or a custom chip designed by Atari? I don't think Coleco could have used TIA without a license if it was an original Atari design. The reason why Coleco won the lawsuit filed by Atari was because the Gemini and expansion module were built entirely from off the shelf parts and didn't violate any Atari patents. Edited October 31, 2010 by OldAtarian Quote Link to comment Share on other sites More sharing options...
+5-11under Posted October 31, 2010 Share Posted October 31, 2010 By the passive components nearby, I'm guessing it's the one on the left. Is the pin-out of the Coleco TIA the same as the Atari TIA? If not, you'll just need to do some sleuthing to figure out which pins you'll need. Welcome to AA! Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted October 31, 2010 Author Share Posted October 31, 2010 By the passive components nearby, I'm guessing it's the one on the left. I agree, but won't be sure till I try I guess... Is the pin-out of the Coleco TIA the same as the Atari TIA? If not, you'll just need to do some sleuthing to figure out which pins you'll need. This is the problem, no one seems to know and its no where to be found on the net, surely i'm not the first to a/v mod a gemini!?!? Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted October 31, 2010 Author Share Posted October 31, 2010 Was TIA a general purpose chip or a custom chip designed by Atari? I don't think Coleco could have used TIA without a license if it was an original Atari design. The reason why Coleco won the lawsuit filed by Atari was because the Gemini and expansion module were built entirely from off the shelf parts and didn't violate any Atari patents. This is exactly why everyone says the gemini can be modded just like a 2600, but can't confirm it. Quote Link to comment Share on other sites More sharing options...
A.J. Franzman Posted November 1, 2010 Share Posted November 1, 2010 By the passive components nearby, I'm guessing it's the one on the left. No guessing required. The two chips on the right bear type numbers SY6507 (CPU) and SY6532 (RIOT). Is the pin-out of the Coleco TIA the same as the Atari TIA? If not, you'll just need to do some sleuthing to figure out which pins you'll need. That is the crucial question, but not difficult to reverse-engineer. Was TIA a general purpose chip or a custom chip designed by Atari? I don't think Coleco could have used TIA without a license if it was an original Atari design. The reason why Coleco won the lawsuit filed by Atari was because the Gemini and expansion module were built entirely from off the shelf parts and didn't violate any Atari patents.This is exactly why everyone says the gemini can be modded just like a 2600, but can't confirm it. The TIA was apparently either not patented, or manufactured under license by so many chip makers, that it did become a de facto "off-the-shelf" part. If I had a Gemini motherboard in my hands, plus access to VCS schematics that I already have on my computer, I could verify the Gemini "TIA" pinout in about an hour or less. Quote Link to comment Share on other sites More sharing options...
Game-Tech.US Posted November 1, 2010 Author Share Posted November 1, 2010 If I had a Gemini motherboard in my hands, plus access to VCS schematics that I already have on my computer, I could verify the Gemini "TIA" pinout in about an hour or less. I have both and a scope, just not real proficient with one yet. What do I look for? Quote Link to comment Share on other sites More sharing options...
Rybags Posted November 1, 2010 Share Posted November 1, 2010 (edited) It'd have to be the one near top left with "Coleco" printed on it. On the other side you can plainly see the 2 chips are the 6532 RIOT and the 6507 CPU. Finding if it's pin-compatible with a 'scope... Get the pinout of the TIA, then use outputs from the corresponding pins: . CSync - there should be a ~ 1 ms pulse at a frequency of just under 16 KHz . Colour out - put a game in, preferably one that has a coloured background. You should get a high frequency wave output from this pin. You might want to use CSync as a trigger when monitoring this pin. You could test other pins too such as the Luma ones. In all cases probably a good idea to have a game running as TIA would probably only output on CSync without one. You also should be able to visually check (or just use the continuity test of a multimeter) stuff like the Data and Address buses, the R/W select, and the RDY line. Also, the Luma pins should go through a resistor ladder, so their ultimate paths/destinations will be similar. Edited November 1, 2010 by Rybags Quote Link to comment Share on other sites More sharing options...
supercat Posted November 1, 2010 Share Posted November 1, 2010 I have both and a scope, just not real proficient with one yet. What do I look for? If your scope is analoguey, Set the scope to trigger off 60Hz line frequency, throw an Asteroids cart in both machines, and look at each pin in sequence. From experience working on my 4A50 cart, many of the pins have very distinctive patterns on an analogue scope while running Asteroids. Quote Link to comment Share on other sites More sharing options...
Jess Ragan Posted August 3, 2013 Share Posted August 3, 2013 http://www.digitpress.com/faq/vcs_tia/vcs_tia.htm It's definitely the chip on the left. It's a Coleco/VTI 73192, as shown on this Digital Press page. Quote Link to comment Share on other sites More sharing options...
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