#+title: Abstraction & ISA
#+date: <2021-11-03 Wed 00:00>
#+author: thebesttv

Abstraction 真是好重要好重要的概念.

感觉 Computer Organization 里最重要的一个概念就是ISA, 它是软硬件的中间层.
软件不必知道底层的硬件, 只需知道ISA就可以运行;
而硬件只需遵从某个 ISA (如 x86, risc-v), 不必考虑上层的软件.

#+begin_quote
The combination of the basic instruction set (the ISA) and the operating
system interface is called the application binary interface (ABI).

ABI---The user portion of the instruction set plus the operating system
interfaces used by application programmers.  Defines a standard for
binary portability across computers.
#+end_quote