Serial port

A serial port on the target can be useful during development for downloading an image or as a failsafe mechanism (e.g. if a checksum fails, you can simply reload the image via the serial port).

A serial loader can be built into the IPL code so that the code can fetch the image from an external hardware port. This generally has a minimal impact on the cost of an embedded system; in most cases, the serial port hardware can be left off for final assembly. Evaluation boards supplied by hardware chip vendors often have serial ports. We supply source code for an embedded serial loader for the 8250 chip.

The IPL process in this case is almost identical to the one discussed above for the Network boot, except that the serial port is used to fetch the image.