In system Programming (ISP): Programming is done „within the system‟ i.e. firmware (IEEE 1394 is wired isochronous high speed serial communication bus) is embedded into the target device without removing it from the target board.
The target device must have an ISP support. No additional hardware is required.
Chips supporting ISP generates the necessary programming signal internally using chip‟s supply voltage.
Target board is interfaced to utility program running on PC through Serial/Parallel/USB port
Serial Protocol for ISP: JTAG, SPI(serial peripheral interface.
In Application Programming (IAP): IAP is the technique running on the target device for modifying a selected portion of the code memory.
This technique is not used for first time embedding of user written firmware.
It modifies the program code memory under the control of embedded applications
Examples: Updating calibration data, look up tables ,Boot ROM etc. in code memory