bips sen:
I did not look at every byte. But they appear to be the same. Your testing also seems to indicate that they represent the same object code.

It is common for 8051 assemblers or linkers that create a HEX file to produce the file in such a way that it only contains the data actually produced by the original source program. The actual output records may even have their base addresses correspond to the "org" statements in the original source code!! You can see this in your example as the first two records start at address 0x0000 and 0x0003 and each contain the 3 bytes that go into the reset and first interrupt vector. The second file you created with the programmer interface software does not know anything about the original program structure and so it reads out the whole program memory including all the unused bytes which are erased at 0xFF values.

Michael Karas