would anyone know what programming language manufacturers use when they make C.O.B (Chip-On-Board)watches.
I have to design a new type of multifunction digital watch, and would rather develop the functions in the same language, to avoid any confusion.

the designer? he'll use whatever he's comfortable in, probably assembly for whatever processor is involved.

the manuf either uses mask programmed chips (pre-programmed straight from the foundry) or uses some sort of in-circuit programming and downloads straight machine code (hex file).