Decided to use the QL to teach my students about multitasking. I suppose I could have used Linux/Unix but with a single user system and complete job control via TK2, seemed the easiest. We'll be getting to Linux/Unix after Thanksgiving so we might play with priorities again then. Students used a web-based emulated QL:
I piqued their interest by mentioning that this was a computer that Linus Torvalds owned before creating Linux...that got their attention. I had everyone typing along with me so we have close to 20 new QLers in their early 20's
They basically had to exec the baton program twice (kept the tail short...like 2) and play with spjob to change priorities (even completely stopping them). I also had them exec the cl program and load test_bas within it and play with spjobs with all three running to see how things would slow down.
I am curious to know what they thought of it being done with a 32K operating system & 128K ram? Perhaps they might ask what the other 4 Gigabytes does on modern computers.
Ruptor wrote:I am curious to know what they thought of it being done with a 32K operating system & 128K ram? Perhaps they might ask what the other 4 Gigabytes does on modern computers.
I made a point of letting them know the size of the OS and comparison with modern Windows. I think the problem they have is with scale and also understanding enough of software engineering to relate the difference. For instance, modern Windows also gives you a lot of graphical resources so I think it's hard for them to understand where those lines intersect with the kernel operations of an operating system. I used car transmission as a metaphor as to why I wanted to use one of the first microkernel preemptive operating systems since it's trickier to get the kind of control with jobs under Windows (think automatic transmission) vs an old operating system (think standard transmission).
It's an interface issue because I'm sure you can control jobs somewhat granularly in Windows though Task Manager gives you some vague job priority rankings and you have to use the resource manager if you want to completely pause a process. I looked into command shell job priority control but that seems overly complex and I wasn't sure if I could get what I wanted. The nice thing on the QL is that it's easy to control how many jobs are running and if you give one job twice the priority of another (think two baton programs) then one seemingly runs twice as fast. So it was a pretty effective demo on how a preemptive kernel has complete job control.
I countered that with a classic Mac OS demo using System 7.5 (I have lots of kernel level experience with the classic Mac OS having hacked its kernel back in the day) and showed them how things are much different (frustratingly) in that environment. That wasn't done via an online webpage since I don't have a virtual form of Mac OS running on the web. So I used my actual PowerBook 180 plugged into the class projectors to demo that. I used the same cl program on both to show how differently they run.
