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Comment by jacquesm | Hacker News Reader

> the guy wrote a multitasking operating system with this approach. I'm pretty sure I couldn't do that.

You'd be surprised at how doable that is if you actually tried. It's the same as every other problem in programming: break it down in to two pieces, figure out which one is the easier, if it is trivial solve it, otherwise recurse.

You'd need an overall sketch of the architecture before you began but once you have that worked out it's 'just programming' to get you to the finish line.

The hardest part to get right is security, especially if you go multi-user, but since you just specify 'multitasking operating system' that one is somewhat limited in scope.

(such thinking probably gave us windows ;) )...

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Thanks, I appreciate the support, but my opps, you caught my initial phrasing before I clarified to disambiguate: I didn't mean to write an operating system; but to write one in Dijkstra's way (ie by showing - proving - that it works before you write it). ugghh I shudder just saying it.

Ah, ok, now I get it :) That was more than just a little bit ambiguous, I completely fell for it.

I'm sorry; I didn't mean to dig a pitfall to entrap a helpful fellow traveler. When I noticed that a reading with the last two sentences as separable was misleading, I edited directly. I think the "sadly" part was communicated though, and I've tucked away your remarks for when I'm confronted by a multitasking OS. I think debugging the race conditions would be nightmarish.

The trick is to write your OS in such a way that you minimize the chance of having races. The way I chose was to mimick 'QnX', a message passing real time OS.

This is also what experience gives you: the ability to predict where problems are likely to crop up so you can avoid them.

Easier to not inject a bug in the first place than to try to find it later.

... and wait for the computer to reboot every time you screw up ...

It can be a slow process with less 'instant gratification' than web programming.

Yes, that was one of the main problems when I was busy with this. I had a guitar footpedal switch wired to the reset button so I didn't have to dive under the desk all the time.

This was before the age of virtual machines on PCs. Getting it to become self hosting took about 6 months or so.

Bochs isn't particularly slow to boot :)

Not these days it isn't. People like this guy and Linus had nothing like that when they were working, though.

@derefr

It is compared to QEMU :)

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