Recent Posts

1

Website and Forum / Re: Why did the site go down just a few days ago?

« Last post by debs3759 on May 01, 2025, 03:54:09 AM »

That's just speculation, most of us have no idea whether it was a network issue or a software issue. Or something else. No point pointing fingers until someone in the know responds.

2

Website and Forum / Re: Why did the site go down just a few days ago?

« Last post by ben321 on May 01, 2025, 02:57:17 AM »

Assuming the server admin is paying their ISP for a static IP address then you shouldn't have this kind of issue. This kind of issue happens issue when the IP address associated with the domain name becomes obsolete due to the IP address being dynamic (ISP periodically changes your IP address).

3

Website and Forum / Re: Why did the site go down just a few days ago?

« Last post by debs3759 on April 30, 2025, 06:11:50 AM »

I think it was down for over a week. That's not unusual, as the server isn't regularly monitored, amd the site admin isn't around much. It is run by volunteers after all (even if the site admin works (or worked) for Intel

4

Programming with NASM / Re: how to switch video modes (switching to VESA video modes too) in protected mode

« Last post by fredericopissarra on April 29, 2025, 02:31:39 PM »

For VESA in protected mode, you gotta use VBE functions, not BIOS interrupts. Check the VBE specs on OSDev wiki for mode info and framebuffer setup. It’s tricky but doable. What bootloader you using? Might help narrow it down.

You can do this only with PMI is available to you. It isn't the case of QEMU and even at ROM BIOS extentions of major modern graphics cards like nVidia's (at least I can't find it using the described method from VBE3 documentation).

5

Programming with NASM / Re: how to switch video modes (switching to VESA video modes too) in protected mode

« Last post by ben321 on April 29, 2025, 07:31:19 AM »

Hi, I am Lukas,
and I am writing my operating system but I have problem with switching video modes ( switching to VESA modes too ) because I don't know how to do it and I don't found any tutorial on it so I need help. I know that in real mode it can by done by using ah = 0x00 and with interruption 0x10, but I am in protected mode so I don't know how to do it. Can someone help me please?
Thanks for any help!

That's because the interrupts work differently in protected mode. In protected mode the CPU ignores the IVT (interrupt vector table) that was used in 16bit real mode, and instead requires you to set up an IDT (interrupt descriptor table). In 16bit protected mode, you might be able to (if you're lucky) get away with pointing the IDT to the same interrupt functions that the IVT originally pointed to (but if not, then you'll need to take the same steps as if you were working with 32bit protected mode). But if you mean 32bit protected mode, then that's not a possible shortcut at all, because the functions pointed to by the IVT are all written in 16bit code, not 32bit code. So you will need to write your own 32bit functions (or 16bit functions if you are talking about 16bit protected mode) for EVERY SINGLE FUNCTION that exists in the IVT. That's 256 functions you will need to write! Not worth the effort, if you are doing anything other than writing an entire operating system. Since I assume you are writing software, not an OS, I would advise you to not bother with this effort, unless you really just want to go through with it for the sake of learning how to do it (maybe as a project in a programming class at a university or something).

6

Website and Forum / Why did the site go down just a few days ago?

« Last post by ben321 on April 29, 2025, 07:11:40 AM »

Just a few days ago the site was down, and it was down for like 2 days. I see it's back up now, but no announcement on what happened.

7

Example Code / Re: "Hello world" with a very simple encoding

« Last post by andyz74 on April 25, 2025, 05:48:11 PM »

A label bassed calculation of the opcodes to decode would really have been convinient, that's for sure. And easy to code too. But to be honest, I'm using micro as editor for programming, and there are shown the line numbers at the left side, so the substraction was really easy too...   

8

Programming with NASM / Re: how to switch video modes (switching to VESA video modes too) in protected mode

« Last post by marknoble on April 25, 2025, 04:37:33 PM »

For VESA in protected mode, you gotta use VBE functions, not BIOS interrupts. Check the VBE specs on OSDev wiki for mode info and framebuffer setup. It’s tricky but doable. What bootloader you using? Might help narrow it down.

9

Programming with NASM / Re: Printing of floating point values

« Last post by marknoble on April 25, 2025, 03:02:57 PM »

Ugh, that "no-PIE" error is such a pain! Been there. Instead of messing with recompiling GCC (total hassle), you could try using puts with sprintf to format your float into a string first. Something like:

Code: [Select]

char buffer[32];
sprintf(buffer, "%f", your_float);
puts(buffer);It’s not as slick as printf, but it sidesteps the linker drama. Another option is write to stdout if you’re feeling low-level, but you’d still need to convert the float to a string manually. I’ve had luck with this on Debian 12, no PIE nonsense required. Worth a shot?

10

Example Code / Re: "Hello world" with a very simple encoding

« Last post by marknoble on April 25, 2025, 03:00:24 PM »

Nice work messing around with this! I’ve dabbled in some assembly too, and it’s always a trip to see how low-level you can go. Your encoding trick with the +18h offset is a cool way to obfuscate things, and I like how you kept it simple but effective. I tried something similar a while back on a 32-bit setup, just playing with XOR encoding for the code section, and it was a pain to debug when I messed up the decoding loop, props for getting it running smoothly! One thing I’d maybe watch out for is that hardcoding the decode length (like 50 bytes) could bite you if you tweak the code later. Maybe a label-based size calc could save some headaches? Anyway, fun stuff, thanks for sharing!