Now, I'm not trying to be offensive, but it's clear that you haven't even thought about this for as much as one second, and you're unwilling to apply even the most basic effort to a search, and you're unwilling to read and follow the forum rules.

Try staying with one thread rather than starting multiples, and try searching via GOOGLE for information about "checksum". It's a VERY simple process, which should already be suggested by the fact it's a "checkSUM."

Consider what happens when you add each byte in the code space together. It won't matter in what order you add them, but usually one starts at one end and stops at the other. If something is in changed, your sum will most likely be changed. The definition of "likely" is a component in the discussion, of course, but for now, it doesn't matter. If you know how to generate code for your MCU, then you know how to add. If you know how to add, then you know how to check the sum. HINT: If you know how to subtract, then you know what value will make the sum result in any desired value.

If you don't know how to make your MCU ADD and SUBtract, then you should probably consider doing something else with your time.

I suspect, however, that this is part of your homework and you've simply made a bet that someone on 8052.COM will be foolish enough to do it for you.

RE