OSDev.org

Just in case people were wondering, I've confirmed this with the official docs:

There is one other important note about Sector 0 of a FAT volume. If we consider the contents of the sector as a byte array, it must be true that sector[510] equals 0x55, and sector[511] equals 0xAA.

NOTE: Many FAT documents mistakenly say that this 0xAA55 signature occupies the ?last 2 bytes of the boot sector?. This statement is correct if ? and only if ? BPB_BytsPerSec is 512. If BPB_BytsPerSec is greater than 512, the offsets of these signature bytes do not change (although it is perfectly OK for the last two bytes at the end of the boot sector to also contain this signature).

Patching it up as we speak

Is it ok if i compile a list of OSfaq offline mirrors and put it on the OSfaq? I would put it onto a single page with a link on the HomePage for everybody to see ;D

i'll rather have it in the "QuickLinkz" thread of this board, since it will mostly be useful when the FAQ no longer work properly

rofl, like for that guy on this topic ???. rofl. I'm going to start a small topic for people to submit links to their mirror if they have one

I'm glad you've made effort for this kind of wiki. It were extremely helpful for my kind of starter. It were useful with it's compact information. Great for getting the overview what's happening there! ;D

I've been getting 403 Forbidden for months. Can this please be fixed? (Using IE6 SP2/WinXP)

I'll say it again. If you can get to the message board, you can get to the FAQ.

The FAQ has no access controls. If your getting a forbidden error, I dont know why..

purevoid wrote: I've been getting 403 Forbidden for months. Can this please be fixed? (Using IE6 SP2/WinXP)

try cleaning your cookies (might be asking for an invalid account or so) ... try desactivating any proxies ... try to see if some friend of yours with same ISP and different configuration can access it ...

try if mozilla or firefox does it better from your system ...

What else could i say ? i never seen that here. i've never seen a phpwiki (afaik, the wiclicker also uses phpwiki. can you access it ?) doing that.

The only good news i can give you is that i uploaded osfaq-offline 2006.01.12 yesterday on sourceforge. That might be better than nothing ...

It wouldn't hurt to check the logs....

Maybe it's something wrong with my ISP, I dunno. Both of my PCs get 403 Forbidden. That's Konq on linux/ubuntu, firefox, opera 8, and ie6 on winxp sp2.

I can't see how a 403 error could happen due to something
the client did, other than who the client is (or a wrong server
setup).

Wasn't there some talk last week about how certain (ISP?)
IP ranges where blocked for reasons of spam or other bad-
ness?

I can't see how a 403 error could happen due to something
the client did

Some form of (invalid) authentification cookie was something i had in mind. Clearly that's not what's going on.

Wasn't there some talk last week about how certain IP ranges were blocked for reasons of spam or other badness?

I don't think that can explain why only the FAQ is blocked for him:

df wrote: I'll say it again. If you can get to the message board, you can get to the FAQ.
The FAQ has no access controls.

Someone (anonymously) added the following to "Can I use some language other than C?" (the italics part is new):

On the other hand, trying to write an OS in interpreted languages like Perl, Java or Basic is unlikely to succeed. There are research projects about it, of course, but nothing that have completely changed the way we write kernels so far. And trying to write it in PHP, Javascript or .Net would just be a proof you've much to learn...

However, if your skill in the language is deep enough, which it should be anyway, there is a way. Namely, write your own compiler, XYZ to ASM.

The person also added the page "write your own compiler", which is empty however.

I have some objections here.

1) I don't think the OS FAQ should extend into compiler-writing techniques. There are other sources available on the subject, and I don't think we here are the ones to significantly contribute to that field.

2) The talk is about interpreted languages. Writing a compiler for a language designed to be interpreted - and expecting the binary to run in a freestanding environment - is no mean feat. And knowing VisualBasic really well does teach you zilch about how to write a compiler for it. The statement quoted above is, in the very least, a bit too strong for my tastes. We would have to rule out a sizeable percentage of regular visitors to this board if we'd apply skill demands like that.

3) Writing a compiler capable of generating freestanding binaries, with acceptable optimization / performance levels, is one hell of a project all in itself IMHO, and I'd consider it a very poor decision for a hobby OS project (like those this site caters for) to chose a language for which no compiler yet exists. (Like in, not taking 10 years but 15 years until something competitive could come from it.)

My first impulse was to delete the new page, rephrase the new paragraph quoted above, and perhaps add an Amazon link to "Compilers Principles, Techniques and Tools" (the "dragon book") for those who really insist in doing this. But I'd like to hear opinions first.

Should we add content on compiler creation, and bear with the influx of related chatter to the wiki this board?

Should we add one page on compiler creation, with a couple of links, mentioning that neither the wiki nor the forum is really the place for related discussion?

Should we add one or two links to the "Can I use..." page, with the mention that neither the wiki nor the forum is really the place for related discussion?

Should we scrap the notion altogether and revert the "Can I use..." page to previous version?

Solar wrote: Someone (anonymously) added the following to "Can I use some language other than C?" (the italics part is new):

On the other hand, trying to write an OS in interpreted languages like Perl, Java or Basic is unlikely to succeed. There are research projects about it, of course, but nothing that have completely changed the way we write kernels so far. And trying to write it in PHP, Java Script or .Net would just be a proof you've much to learn...

However, if your skill in the language is deep enough, which it should be anyway, there is a way. Namely, write your own compiler, XYZ to ASM.

The person also added the page "write your own compiler", which is empty however.

I have some objections here.

1) I don't think the OS FAQ should extend into compiler-writing techniques. There are other sources available on the subject, and I don't think we here are the ones to significantly contribute to that field.

i don't think either. plus writing a compiler for language XYZ is no different from writing an interpreter for XYZ (plus support libraries) -- at least from the OS point of view (OS code won't care whether it's interpreted or running natively, i mean).

Both are out of scope, extremely ambitious and probably not a wise way to do thing, imho.

My first impulse was to delete the new page, rephrase the new paragraph quoted above, and perhaps add an Amazon link to "Compilers Principles, Techniques and Tools" (the "dragon book") for those who really insist in doing this. But I'd like to hear opinions first.

Yes, i think too, that we might point people that think it's a good idea to available resources with appropriate warning saying that choosing that option is like going on quest for the Graal...

Should we add content on compiler creation, and bear with the influx of related chatter to the wiki this board?

honnestly, no. it's completely out of the FAQ's scope ...

Should we add one page on compiler creation, with a couple of links, mentioning that neither the wiki nor the forum is really the place for related discussion?

having it inline in the "can i use XYZ" should imho be enough. and reminding there that it's another (huge) and unrelated problem to OS deving.

Should we scrap the notion altogether and revert the "Can I use..." page to previous version?

no, i don't think so. Since the question has been raised, it is worth to take into account the fact that people have felt the question unanswered while reading the FAQ.

Though writing one's own language and own compiler to write his own OS in favourite language is somehow the natural extension of writing one's own OS to have one's favourite API to write one's webbrowser, it is (imho) like starting to build a car by designing a new way to melt iron (no, a new screwdriver doesn't match here: too easy to design)...

(Discussion on whether BASIC should be listed as interpreted language or not removed upon request, as it doesn't really change the point of the Wiki page in question - you need to provide the necessary runtime to use language X, whether that is an interpreted or a compiled language.)

Solar: true. However, with an interpreted language you probably *also* need to provide a virtual machine or interpreter (I don't think you can use whatever comes with that language). So that adds to the burden.