Explain the difference between a subroutine & macro.
It is inefficient to have to write code for standard routines. For instance reading a character form the keyboard or saving a block of data to disk. Standard routines are available known as library routines. They might be called up macros and many of the most useful routines are available as operating system calls. A call to a macro is a single command, which can be changed by many commands that set put into the programme where the macro name is encountered. A set of common instructions that can be used in a program in known as a subroutine.