Homebrew for Epoch Cassette Vision or Bandai Super Vision?

Discussion of development of software for any "obsolete" computer or video game system. See the WSdev wiki and ObscureDev wiki for more information on certain platforms.
Dr.Wily
Posts: 11
Joined: Thu Feb 02, 2012 7:05 am
Location: Skull Castle
Contact:

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Post 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.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Post 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.
Dr.Wily
Posts: 11
Joined: Thu Feb 02, 2012 7:05 am
Location: Skull Castle
Contact:

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Post 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.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: Homebrew for Epoch Cassette Vision or Bandai Super Visio

Post 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...
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

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

Post 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.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

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

Post by lidnariq »

Random discussion on the discord led me to look at Mr. Oguchi's website again today, and I noticed that he's been very productive in the past few years.

Oguchi-rd.com now has instructions on how to dump the program and graphic data from most (all?) the games, lots of nice pictures of the inside of the hardware, as well as providing the dumps for eight of the games. He's also provided a schematic to convert the µPD777's luma/chroma/B-Y/R-Y signals into analog YPrPb and a canonical 27-color (six hues of two brightnesses and two saturations each, plus black, white, and grey) palette, and videos of the same eight games being played using this converter.
Post Reply