Contents|Index|Previous|Next I/O support code Most applications use calls to the standard C library. However, when you initially link libc.a, several I/O functions are undefined. If you don’t plan on doing any input or output, you’ve no concerns; otherwise, you need to create two functions, open() and close(). These don’t need to be fully supported unless you have a file system, so they are normally stubbed out, using kill(). sbrk()is also a stub, since you can’t do process control on an embedded system, since process control is only needed by applications that do dynamic memory allocation. It uses the variable, _end, which is set in the linker script. The following routines are also used for optimization.  -inbyte Returns a single byte from the console.   -outbyte Used for low-level debugging, takes an argument for print() and prints a byte out to the console (typically used for ASCII text). Top|Contents|Index|Previous|Next <