4 ms·

Years ago I taught a high school typing class in a K-12 school. The school didn't have the funds to get a commercial typing program so I wrote my own typing pr

Years ago I taught a high school typing class in a K-12 school. The school didn't have the funds to get a commercial typing program so I wrote my own typing program. It evolved over time with features to help me track the students' progress etc. One day we had a school open house where all the parents could come to school. We had a bunch of different activities set up in different classrooms and I ended up getting assigned to the 3rd grade classroom to set up my typing program so anyone coming through could test their typing speed. It was a DOS program and I didn't want people using anything other than my typing program, so I modified it so you couldn't quit the typing program. Over the course of the day the 3rd graders were hanging out in their homeroom not really doing anything productive. Of course the computer was a novel attraction and they were just smashing keys and exploring my program's UI. Eventually at one point I noticed that they had somehow crashed my program with a segfault in what had otherwise become a pretty stable piece of software. To this day I have absolutely no idea what the bug was.

BruiseLee 6y ago
Are you sure it was a segfault? DOS did not have any memory protection, so segfault would be impossible. Or maybe you used some protected mode DOS extender?
- tachyonbeam 6y ago
  What happens if you try to read from a null pointer in DOS?
  - pas 6y ago
    You get what is at 0x0000 ?
  - vngzs 6y ago
    I haven't actually tried this, but based on my understanding of the MS-DOS memory model it should read the contents of memory at address 0.
    - hvdijk 6y ago
      This is correct, and address 0 is the start address of the interrupt vector table, so there are good reasons why you might read from it.
- mightybyte 6y ago
  My memory is getting a little fuzzy. I think the machines we were using were running Windows 98 or perhaps Windows 95. But I didn't want people to be able to do other things on the computers that day as the whole point of the endeavor was to emphasize typing skill, so I looked for some kind of way to make it impossible to do ALT-TAB to switch to a different program. I was thinking I booted it up in DOS only but I also might have run it full screen in Windows and just hoped nobody knew about ALT-TAB. :P
rexpop 6y ago
> The school didn't have the funds to get a commercial typing program so I wrote my own typing program. Off-topic, but: It seems absurd, to me, that such a conclusion could ever be reached. Obviously, from my perspective, the economies of scale, the infrastructure, overhead, and institutional resources available to programmers at a dedicated software development firm would produce an application at better quality per dollar (however you measure it) than a high school teacher in their off-hours. To me it seems that it's certainly not cheaper for us as a society, as a species, and only appears so because you are under-paid. If you were paid your actual worth, the school would say "we don't have the funds to develop this in-house, and had to buy a commercial typing program off-the-shelf, despite its loose fit for our use case." How can we, as rational members of society, abide this?
- kelnos 6y ago
  Agreed. Where I work there is a tool that's used in hundreds of our internal services. It was written in-house during one of our hack weeks years ago, and later we open-sourced it. Despite the fact that the org relies so heavily on it, it's completely unfunded; two employees improve and maintain it in our free time. (We do have a few outside contributors, too, which is awesome!) That's not exactly the same situation, but I think this kind of short-sightedness is pervasive in our culture, in every walk of life.
- jodrellblank 6y ago
  How do you commercially produce "better quality per dollar" when the high school teacher's off-hours cost the school $0 and they get infinite quality per dollar?
  - rexpop 6y ago
    Calling work done in off-hours "$0" is magical thinking. That teacher costs a lot to maintain. Those of us who are employed full-time don't really have "off-hours", and regardless of the intensity with which we focus in a given 60-minute period. Sometimes, while at work, I am thinking of leisure. Sometimes, while at leisure, I am thinking of work. At the end of the day, the school pays their employee. And the rest of society pays them during "off-hours", e.g. in depreciation of common resources if, say, they drive on the road. My point is that people cost society to keep alive, but some of those people are better equipped for certain tasks than others. The question is only where do those costs come from, and to what particular efforts are the particularly-equipped assigned.

BruiseLee 6y ago

Are you sure it was a segfault? DOS did not have any memory protection, so segfault would be impossible. Or maybe you used some protected mode DOS extender?

tachyonbeam 6y ago
What happens if you try to read from a null pointer in DOS?
- pas 6y ago
  You get what is at 0x0000 ?
- vngzs 6y ago
  I haven't actually tried this, but based on my understanding of the MS-DOS memory model it should read the contents of memory at address 0.
  - hvdijk 6y ago
    This is correct, and address 0 is the start address of the interrupt vector table, so there are good reasons why you might read from it.
mightybyte 6y ago
My memory is getting a little fuzzy. I think the machines we were using were running Windows 98 or perhaps Windows 95. But I didn't want people to be able to do other things on the computers that day as the whole point of the endeavor was to emphasize typing skill, so I looked for some kind of way to make it impossible to do ALT-TAB to switch to a different program. I was thinking I booted it up in DOS only but I also might have run it full screen in Windows and just hoped nobody knew about ALT-TAB. :P

rexpop 6y ago

> The school didn't have the funds to get a commercial typing program so I wrote my own typing program. Off-topic, but: It seems absurd, to me, that such a conclusion could ever be reached. Obviously, from my perspective, the economies of scale, the infrastructure, overhead, and institutional resources available to programmers at a dedicated software development firm would produce an application at better quality per dollar (however you measure it) than a high school teacher in their off-hours. To me it seems that it's certainly not cheaper for us as a society, as a species, and only appears so because you are under-paid. If you were paid your actual worth, the school would say "we don't have the funds to develop this in-house, and had to buy a commercial typing program off-the-shelf, despite its loose fit for our use case." How can we, as rational members of society, abide this?

kelnos 6y ago
Agreed. Where I work there is a tool that's used in hundreds of our internal services. It was written in-house during one of our hack weeks years ago, and later we open-sourced it. Despite the fact that the org relies so heavily on it, it's completely unfunded; two employees improve and maintain it in our free time. (We do have a few outside contributors, too, which is awesome!) That's not exactly the same situation, but I think this kind of short-sightedness is pervasive in our culture, in every walk of life.
jodrellblank 6y ago
How do you commercially produce "better quality per dollar" when the high school teacher's off-hours cost the school $0 and they get infinite quality per dollar?
- rexpop 6y ago
  Calling work done in off-hours "$0" is magical thinking. That teacher costs a lot to maintain. Those of us who are employed full-time don't really have "off-hours", and regardless of the intensity with which we focus in a given 60-minute period. Sometimes, while at work, I am thinking of leisure. Sometimes, while at leisure, I am thinking of work. At the end of the day, the school pays their employee. And the rest of society pays them during "off-hours", e.g. in depreciation of common resources if, say, they drive on the road. My point is that people cost society to keep alive, but some of those people are better equipped for certain tasks than others. The question is only where do those costs come from, and to what particular efforts are the particularly-equipped assigned.