What are the disadvantages of an embedded computer?

Embedded computers are devices that perform a specific function in a higher assembly. The limitations of any particular embedded computer are the specifications for which it was designed. I once designed, fabricated, and coded a microprocessor based add-on for an internal navigation system. Within the INS was a single pin that was modulated with a series of several hundred bits in a ring format. All the µprocessor had to do was find the frame start pattern and demodulate the data into a memory array, then broadcast selected information out of a UART (COMM port interface). This is an example of an embedded computer. It had a specific function that it performed continuously. Some other examples of embedded computers are the Video, Sound, NIC, and/or Modem cards you may find in the backplane of your PC. Most of these functions are performed in (embedded into) the Chipset of the PC, but the design of the motherboard allows you to turn off any of these features if you want to upgrade to a better board.