Exercise 3: Two Real Models, Not One Interface With Two Syntaxes — Possible Solution
====================================================================

WHAT "ONE INTERFACE, TWO SYNTAXES" WOULD MEAN
------------------------------
That framing would suggest Linux and Windows are doing the SAME
underlying thing — asking the OS for a service through a shared kind
of mechanism — just spelled or encoded slightly differently on each
platform, the way, say, AT&T and Intel syntax (assembly2-3) describe
the identical underlying instructions with different notation.

WHY THAT'S NOT WHAT'S ACTUALLY HAPPENING HERE
------------------------------
Per this chapter's own explanation, Linux and Windows don't share one
underlying mechanism at all. Linux provides a genuinely stable,
application-facing syscall interface, directly invoked with a
dedicated instruction (SYSCALL). Windows deliberately does NOT expose
an equivalent stable, application-facing syscall interface at all —
its own internal syscalls are private and can change, and the actual
stable, sanctioned contract is an entirely different kind of thing:
an API of ordinary callable functions living in DLLs. These aren't
two notations for the same underlying operation; they're two
genuinely different KINDS of contract, one built around a direct
kernel-entry instruction, the other built around ordinary function
calls into user-space library code that happens to talk to the kernel
internally.

THE CONTRAST WITH ASSEMBLY1-8's TRAP
------------------------------
Per assembly1-8, LC-3's TRAP was ONE single mechanism — the same
instruction, the same vector table, the same fixed set of OS
services, guaranteed identical on every LC-3 system that exists,
because the LC-3 specification itself defines the OS services
directly. There was never a question of "which flavor of TRAP does
this particular LC-3 system use" — TRAP simply IS the interface,
everywhere, always. x86-64 has no equivalent single specification
defining what "the OS interface" is — it depends entirely on which
actual operating system is running, and the two major real-world
options (Linux, Windows) settled on fundamentally different kinds of
contracts, not just different spellings of the same one.

WHY THIS WORKS AS AN ANSWER
------------------------------
It explains precisely what "two syntaxes for one interface" would
require (a shared underlying mechanism), shows that Linux's and
Windows's actual approaches don't share that underlying mechanism at
all (a direct kernel instruction vs. an ordinary function-call
surface), and contrasts both against assembly1-8's own TRAP as the
genuine single-mechanism baseline this chapter is measuring the
divergence against.