5/19/15

Retrobit Project: Castlevania 3

Alright so my goal is simple-ish. Modify my retrobit retron 1, aka my Retro Entertainment System (RES) to play  Castlevania 3, using the following two links as primary references to prove it's possible and help guide me.

https://www.youtube.com/watch?v=BNXs9kcFAPI

http://theisozone.com/forum/viewtopic.php?f=20&t=22444

Starting off, the video does not provide any look into the retron 1 itself to have an idea of how it was modified. It uses Hyperlink Retro Entertainment System and NOT retrobit which I have, but they should be very similar. The video shows that it is possible to get past the start screen and enter gameplay.

According to the video a 7404 inverter is required to make this work. By passing the A13 through the 7404 inverter into the NOAC the game should work. Now I don't really know technology too well so I don't know what any of this means, let alone what A13 or NOAC stands for.

Upon further research I came across the forum link where someone is discussing modifying it himself, but instead he possesses a FC Twin console.


 A photo of Majestic_Lizard's FC twin as he discusses the modification. His instructions with this photo as reference;
"* pin 58 (connected to the 7400 gate's pin 3)
* pin 65 (connected to the 7400 gate's pin 1 & 2)
* pin 72 (connected to the 7400 gate's pin 7)
* pin 36 (connected to the 7400 gate's pin 14)
Ignore the comment about the cut traces unless they are linked on your FC Twin. On mine they were not."
Not sure what he means by "ignore the comment traces unless they are linked on your FC Twin". What are these 'traces' he speaks of? Apparently it was a moot issue though as his didn't require it at any point. 


The person posting claimed this photo was using a 7404 inverter. Is there a difference between 7404 and 7404n?


This one claims to be for 7400 instead.



To cross reference, here's a photo of the back of my personal retro-bit RES as the one provided allegedly comes from hyperlink. I also have no idea why the image gets flipped upside down when I upload it to this site. Repeatedly.






The picture above should hold true for the design. I found it through a random google search while trying to figure out the differences. It appears they function principally the same, with their input and output at least. 



I noticed that the illustration had a triangle with a circle on it, which according to wikipedia is the symbol of a not gate (AKA a inverter). Sounds correct as the original instructions were for a 7404 inverter. Is that what the 'n' at the end of 7404 stands for? Are all 7404 inverters?


7400 for comparison. Not exactly sure what's going on here.


Apparently 7404 is similar except instead of being a simple not gate (inverter) it can work as a NAND, combining two inputs into a single output each. Should be the exact same results as long as you didn't accidentally use the second input as a output I suppose?


Hoping to endeavor upon this project in a few days, using wire salvaged from a dead sound station.




There was an error in this gadget