We normally don’t care about abstractions in software, because they exist to hide details we shouldn’t need to care about. However, sometimes, we do need to know the detail. An essential part of how PHP works involves memory management. This month we’ll see new ways to think of memory itself; we’ll also introduce a learning tool we’ll be using in upcoming articles. We’ll be simulating an ancient mainframe computer, and its hard-wired operator console, using modern text messages.