The "PIC Language"
The native PIC language is RISC assembler. Almost all PIC data sheets contain the full instruction set. Microchip publish a full Intergrated Develpment Environment (IDE) for it and it’s COMPLETELY FREE! You can step through your code on-screen without promming it into the PIC and there are only 31 (depending on the PIC) instructions to learn. Given that PICs are also COMPLETELY FREE (engineering samples) your only expenditure would be a programmer. You can build one (eg JDM) for about $10 and the software to drive it is also COMPLETELY FREE.
So, there you go. No fancy boards, no fancy bootloaders, the whole thing’s free (except the programmer). All you have to do is learn 31 little instructions.
Actually, apart from the language, the fundamental difference between a PIC and most other pic-based solutions is the bootloader. (Can anyone clarify if BS has a bootloader?) The raw PIC is programmed by a pair of special programming pins. In the case of “other” PIC-based controllers, these pins are used in the factory to program a small piece of code called a bootloader. Thereafter, teh user doesn’t have to use the programming pins because your program is pushed into the PIC’s serial port (a different pair of pins) THROUGH the running bootloader program (hence, it’s also sometimes called “through programming”).