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Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Posted: Wed Nov 28, 2018 11:07 am
by Dr.Wily
Hello,

There is some thoughts on the real pinout of cassette vision CPU ? I doubt that pin 15 is the composite video signal. When I plug on a TV there is no image. Just a garbled screen.

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Posted: Wed Nov 28, 2018 1:20 pm
by lidnariq
Earlier in this thread is the research I did two years ago: https://forums.nesdev.com/viewtopic.php ... 30#p176030

You probably need an amplifier of some sort to connect the VIDEO pin to a TV; it probably can't directly drive a 75Ω input. The original Cassette Vision used a big pile of transistors and a 4050 hex inverter IC.

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Posted: Fri Nov 30, 2018 12:50 pm
by Dr.Wily
Thanks, I already read this topic but pin 15 seem to be luminance not directly composite video.

The purpose is to add composite video to a Cassette Vision jr. who only has RF out.

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Posted: Fri Nov 30, 2018 12:57 pm
by lidnariq
Then you'll have to mix luma and chroma. This isn't exactly hard, but you may wish to reverse-engineer what the original mainboard is doing, and find where they're combined, instead of rebuilding it from scratch.

Alternatively, a TV with an S-video input...

Re: Homebrew for Epoch Cassette Vision or Bandai Super Vision?

Posted: Thu Jan 23, 2020 1:45 am
by lidnariq
Following up on this from years ago, it turns out that Sean Riddle decapped one µPD777:
https://seanriddledecap.blogspot.com/20 ... -post.html

Of course, Mr. Oguchi (same link as last time) also shared his original documentation of this part also, complete with a block diagram of what's where on the die, so it's kinda fun to compare the original drawings (even if I unfortunately can't make heads or tails of the Japanese writing) to the picture of the die. Note that Mr. Oguchi's documentation places the RAM (896 whole bits) in the top right corner, while Sean Riddle's decap places it in the top left.