Nope. It generates an error containing the OS version, or returns the OS version. It is only displayed if the user program *CHOOSES* to display it.
Or, as you've stated you're calling them from BASIC, use the BASIC API, ie just...... CALL &FFxx.To call them on a BBC from BASIC: You have to jump to the address of the routine directly, eg A%=0:CALL &FFF4 jumps to OSBYTE 0.
To call them on RISC OS: There is a special command called SYS, so: SYS"OS_Byte",0 is the equivalent.
The WHOLE POINT of Acorn's philosphy of API independance is to avoid programs that do:
IF platformX THEN blah ELSE IF platformY THEN blah ELSE IF platformZ THEN blah
when all the 'blah's can be done with the same identical bit of code
IF (universe) THEN blah
which reduces to:
There is absolutely no need to do
IF riscos THEN SYS "OS_Byte",thing ELSE A%=thing:CALL &FFF4
when the whole point of Acorn's API philosphy is that you do