[cctalk] Re: terminology [was: First Personal Computer]

Is RT-11 a "real operating system"? What about RT-11 SJ? I would consider it to be one. For that matter, what about OS/360 PCP? That's a single task OS, just like RT-11 SJ only much less efficient. Is FIG-FORTH an OS? What about POLYFORTH or ZeptoFORTH? The picture gets particularly muddled when you look at RTOS. For example, it's well known in hard real-time OS that using interrupts is not necessarily a good plan. A very successful storage system I worked on ran on a dual core MIPS system. One core ran NetBSD; the other ran a home-grown RTOS called QRQ that used a polling loop (and no priorities) rather than interrupts. The benefit of such a design is that its time bounds are easy to establish, unlike interrupt driven systems where that is certainly harder and not always possible at all. I'd say an OS is a software system that runs on bare metal (or equivalent, like a VM) and offers a set of services intended to make creating and running applications easier. In that sense, RT-11 SJ or OS/360 PCP are operating systems, just as Linux is. QRQ is on the edge (it's written for a single application). Similarly, I would not call FIG-FORTH an OS, nor those other FORTH systems, though admittedly it's also a bit fuzzy. paul