I don't understand this line of code: EXTRN NUMBER (?ABD?CORE) EXTRN is external variable ? NUMBER is a data type? And what is (?ABD?CORE)? Thanks for letting me know.
"You can find it in A51 manual." Go to the 'Books' tab in the uVision Project window (you can also use Help/Open Books Window in later versions); the manual you require is Assembler/Utilities under Tools User's Guide It's A51.pdf in the C51/HLP folder in your installation.