[TUHS] Abstractions

[Otto Moerbeek]

On Sat, Feb 20, 2021 at 06:09:42PM -0500, M Douglas McIlroy wrote:

> >  - separation of code and data using read-only and read/write file systems
> 
> I'll bite. How do you install code in a read-only file system? And
> where does a.out go?
> 
> My guess is that /bin is in a file system of its own. Executables from
>  /letc and /lib are probably there too. On the other hand, I guess
> users' personal code is still read/write.
> 
> I agree that such an arrangement is prudent. I don't see a way,
> though, to update bin without disrupting most running programs.
> 
> Doug

I always wonder how to distunguish data and programs when people want
to separate them. One person's data is another person's program and
vice versa. Think scripting, config files, grammar definitions,
postscript files, exectuables to be fed to emulators, compilers,
linkers, code analysis tools, the examples are endless.

Turing already saw that form the theoretical point of view, others
(like Von Neumann) more from the practical persppective.

Data = Programs.

	-Otto