Answer:

The string buffer line is defined in doLines. No copy is made of the characters in the buffer. However, other subroutines have access to the buffer since its address is passed as an argument (in $a0) to them. This technique is very common in "C" although, of course, the syntax for doing it is different.

End of the Chapter

You have reached the end this chapter. It would be a capital idea to review the following. Click on a subject that interests you call up the page where it was discussed.

return address, on the stack Pushing and popping the return address.
registers, saving on the stack Pushing and popping registers.
Stack-based Linkage Convention Stack-based Linkage Convention.
prolog The prolog and epilog of a subroutine.
activation Activation of a subroutine.
activation chain Activation chain.
Algol Algol and Pascal