The plate at the top of the stack was the last one added. It will also be the first one removed.
Stack-like behavior is sometimes called "LIFO" for Last In First Out.
The data elements in our stacks are 32-bit words. In general, stacks can be used for all types of data. But in these chapters, stacks contain only 32-bit MIPS full words.
The picture shows a
stack of MIPS full words.
The stack pointer register $sp
by convention points at the top item of the stack.
The stack pointer is register $29.
The mnemonic register name $sp is used by the
extended assembler.
In the usual way of drawing memory the stack is upside-down. In the picture, the top item of the stack is 81. The bottom of the stack contains the integer -92.
Before the operating system starts your program it ensures
that there is a range of memory for a stack and puts
a suitable address into $sp.
If an item of data (say the value 103) is added to the stack, where will it go?