TRIPOS and memory protection

Ethan Dicks ethan.dicks at
Tue Jun 24 02:43:16 CDT 2008

On Tue, Jun 24, 2008 at 08:56:13AM +0200, Eric J Korpela wrote:
> MC68000 versions of TRIPOS (including AmigaDOS) definitely had no
> interprocess memory protection.  I don't know if later versions of
> AmigaDOS implemented protection if a hardware MMU was available or
> even whether they were still considered TRIPOS derivatives.

Oh... I should probably point out that AmigaDOS was pretty much always
tied to its TRIPOS roots, but that the DOS was only part of the software
running on the system - the underlying message-passing layer was "Exec",
then "Intuition" was the window manager.  AmigaDOS was the part worried
about loading code segments and the filesystem and system directory
structure (where to put scripts and binaries and icons and such).

Device drivers and libraries (quite similar internally) and processes
and so on, was part of Exec.

It's quite a complex system, one reason for the multiple phonebooks
for a reference guide - very little of that, though, is AmigaDOS.

I think I was an Amiga developer for four or five years before I
ever saw the AmigaDOS manual.  From day one, though, I had the
RKMs (ROM Kernel Manuals) and used them *lots*.  You pretty much
needed them for any code that had to open a screen or a window,
or that would work with disks below the file layer (block access
and such) or that fiddled with audio.  You could get away from that
level of involvement if you just did things with standard sorts
of C functions, curses, file I/O, etc., but not for anything deeper.

So while AmigaDOS may have been what you saw when you interacted
with a CLI window, and it certainly got invoked if you did stdio-
sorts of things, as a part of the whole, it wasn't a very big
chunk of "The Amiga".

I still hate BCPL and BPTRs, though.


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