Funny enough, I was forced to program in exactly this way, when I was first learning to program. But not in the 1970s... in the year 2001! Why? Because my firs

Funny enough, I was forced to program in exactly this way, when I was first learning to program. But not in the 1970s... in the year 2001! Why? Because my first exposure to programming was the semi-graphical scripting "language" exposed by the game-development tool "RPG Maker 2000." For those who haven't seen RM2K scripting before: picture a cross between Scratch and Emacs Paredit mode. (E.g. https://forums.rpgmakerweb.com/data/attachments/21/21958-f8978e9d268a8359ef8547ff5736de90.jpg https://forums.rpgmakerweb.com/data/attachments/21/21958-f89...) It's presented as textual, but you can't edit it like text — only as blocks with associated properties dialogs. And, of course, that scripting language in RPG Maker doesn't have anything so fancy as a stack. Want some reusable subroutines? Well, you better believe you're allocating secret global variables for their parameters — no re-entrancy for you! --- Mind you, thinking back on it, it's probably possible to implement both registers and a runtime stack in RPG Maker 2000, given sufficient stubbornness. Both features seem easy enough at first: you can do pseudo-"registers" like the zero page on a 6502; and you can do a stack through indirect variable access (https://rpgmaker.net/tutorials/523/ https://rpgmaker.net/tutorials/523/). The problem with both of these, though, is that RM2K actually has concurrency in the form of "parallel process" scripts — so any use of either of these abstractions by these parallel processes, will have different "threads" stomping all over one-another's state. So you'd actually need multiple "zero pages" and "stacks" — one for each "virtual core" — and then you'd need to somehow assign/bind/schedule the "virtual cores" to parallel scripts (i.e. somehow get each script its own privately-known "stack pointer.") Which, to be stable in the face of race conditions, would normally require something like mutexes... Knowing the bloody-mindedness of RPG Maker gamedevs, I'm sure someone did come up with a way to trick some runtime feature into acting like a mutex. But I'm genuinely scared to know what it was they did.