Amiga Roots, TRIPOS - Off Topic, was Re: Exploring early GUIs

On Sep 22, 2020, at 03:02, Peter Corlett via cctalk <cctalk at classiccmp.org> wrote: ?On Mon, Sep 21, 2020 at 11:29:14PM -0500, Richard Pope via cctalk wrote: Er, no. The Amiga's operating system is a pre-emptive multitasking microkernel which uses asynchronous message-passing betwen subsystems, which is not the Unix way of doing things at all. Unix provide libraries of synchronous procedure calls which block the caller until the job is done. Although "AmigaDOS" appears prominently in the terminal as one boots Workbench, that's only the filesystem and command-line shell. Due to time pressure, they bought in TRIPOS and filed off the serial number. TRIPOS is a fairly clunky thing written in BCPL that never sat well with the rest of the system, but it was quite probably the only DOS they could buy in which worked in a concurrent environment. TRIPOS is the reason why disks were slow on the Amiga. The other bit that got reduced from a grander vision was the graphics, which became blocking libraries rather than device drivers. The window manager ran as its own thread which gave the illusion of responsiveness. The "X Window System" (not X-windows or other misnomers) is an ordinary[1] Unix process which provides low-level primitives for a windowing system. "Workbench" is just an ordinary AmigaDOS process which provides a file manager. You can even quit it to save memory, and the rest of the GUI still works. They are not the same thing or "based" on each other at all. [1] Well, some implementations are setuid root or have similar elevated privileges so they can have unfettered access to the bare metal and thus tantamount to being part of the kernel, but that's basically corner-cutting by a bunch of cowboys and it is possible to do this sort of thing properly without introducing a massive security hole.