The Bydo Core only refers to the unknown and mysterious secret bioweapon and evolving supercomputer leader that serves as the final boss of most of the R-Type games.
The Bydo Core was created by Humans in the 26th Century as the source of the Bydo creatures, who were also created by Humans in the same century. However, an error activated the Bydo Core too early in the Solar System and the creation attacked the humans. As a result, the humans banished the Bydo Core into another dimension where it began to evolve, grow, reproduce, and hold a grudge against its enemies. It then found a way to return to the Humans' dimension (in the 22nd Century), through a different solar system. The Bydo Core quickly assimilated the solar system it had exited the other dimension from, creating the Bydo Empire. The monstrous life-forms created by the Core then made a beeline to Earth, taking over everything in their way.
In the original R-Type, The Bydo Core looks like a green, wizened dwarf-like creature with an eye embedded in his forehead. A fleshy gateway separates the Core from the external world and it opens occasionally for the Core to cough out wins. Firing a Force into the Core while the portal is open is the best way to damage it. The trick is surviving long enough for the Force to deal lethal damage.
Manths also accompany it. if you have a blue laser crystal you can make a beam go behind it and damage the back embryo.
Bydo Dimension. It is called Mother Bydo in this game. her hands shoot homing energy balls and lasers. after enough damage her mouth will open to cough up bydo and will stay open until all bydo are offscreen, during this time she is invincible. she will do this twice and on the third time her head will be destroyed and you can inflict damage on her body. if you wait too long without hurting her body, she will grow a new head and you will have to repeat the process until her body is destroyed. then you will have to damage her arms which will fly across the screen and spin in place until the bydo dimension's portal starts to close. the hands will try to keep the portal open while mother bydo's body reappears and spits energy balls. when you deal enough damage to her head, it will open wide which gives you a chance to fire your force into her mouth and will push her into the bydo dimension. if you wait to long to shoot your force, she will spew a horde of energy balls
A Bydo created in the lab that repeatedly spews out all kinds of matter and energy. It can deliver any Bydo attack.
The Bydo Core is called the Ebon Eye in this mission. When defeated, the Ebon Eye's death throes pull in the Space Corps armada. Though a few squads of R-craft can be seen escaping, the majority of craft and all battleships are absorbed by the Bydo. The armada's commander survives as a residual intelligence, seemingly unaware that they've become Bydo. This unlocks the Bydo campaign.
Bydo? Ebon Eye -Eye of Darkness-
Source of the Bydo life forms. Surrounded by huge thrusters living (?) within its walls.
See video of R-Type's final boss fight on YouTube here).