1st, Sharp/Santec where the same US corporation. They recently split, with Santec getting out of the machine tool end. Sharp is the builder and have their own factory in Taiwan. If you go to Sharp US headquarters in Torrance, CA, 1/2 the building is Sharp, the other 1/2 Santec. Check out google maps, you'll see.
Mega was company started by Don and Gary of Machining Time Savers (now HFO-Anaheim).
They would buy naked machines, graft on a cnc (usually Anilam) and sheet metal and for a few years where considered a machine tool builder. They actually had distributors throughout the country. But, I'm sure uncle Gene (Haas) was not too hip with it and they shut down ops. Google Machining Time Savers and give them a call, they probably still have all the documentation.