but in firmware you just don't simply copy the code for one application and write it in a new chip and expect it to work in another application. Suppose there are two spotwelder controllers both used 8051 chips designed by two men working for the same company chances are that their hardware matching each other are very rare if none exitance so the codes cannot be swapped. but in real situation here in the less developed countries we do copy code some time, this is the story: since this company bought 15 terry loom machines long time ago but the manufacturer can not provide support any more(went bankrupt) and they has to program their loom via the comm box assy which uses a 8031 so they agreed to pay, i agreed to design them new assy using the 89s52 big hole in their budget but every body happy.Now they has two cutting machines which also out of support a new design was out of question so is writing new code. so i hacked the code from a still working machine write a new MCU plug it in the defective one and every body happy too. no! i did it just to save an old machine, no! i don't intend to copy new pcb to make another one the copying and writting end there.that might be why some one some time ask questions about reading code from MCU
Khanh