The code does alot of IO port operations. Keil uses SFR and SBIT declarations whereas the AVR code uses defines to set IO port locations and byte operations to set/clear/test bits. There has to be a better way than slogging through the text conversion and then slogging through the debug???
In the list of threads, this one appears as "porting C code from AVR to 8051" - so nobody is going to guess that there might be a question about multimeters buried in it, are they?
Why don't you just start a new thread, properly, and ask your question there?