Learning Challenge: ZX Spectrum machine code: Day 16

Day 16 and I'm playing around with the stack on the ZX Spectrum (using MONS4). The stack is a really neat concept and I can't imagine modern computing without it. blame Alan Turing for the concept of a stack (though instead of push and pop he used the terms bury and unbury). Also Toni Baker has the best analogy for stacks I have ever seen. Instead of the tired "plates" analogy she likens the stack to a stack of boxes. You can only stack on the top and can play with the contents of the top box with ease. Much less confusing than the traditional dish stack analogy.