Search found 7 matches

by scorpion007
Sat Jun 07, 2008 5:45 am
Forum: Article Feedback
Topic: CRT design bug?
Replies: 0
Views: 27001

CRT design bug?

In the CRT article, you define NULL as follows: #ifdef __cplusplus extern "C" { #endif /* standard NULL declaration */ #define NULL 0 // <- This happens unconditionally! #ifdef __cplusplus } #else /* standard NULL declaration */ #define NULL (void*)0 #endif If I'm not mistaken, you define NULL twice...
by scorpion007
Sat Jan 26, 2008 4:10 am
Forum: Beginning OS Development
Topic: "Protected Mode" tutorial question
Replies: 3
Views: 8747

Ah, that makes perfect sense! Thanks. The reason why it makes perfect sense is that each entry is exactly 8 bytes long, so there's no point in wasting space by allowing non-multiple of 8 indices. Each index (bit 3-15) is basically a scaled index into the table, I just didn't realise the processor pe...
by scorpion007
Thu Jan 24, 2008 7:57 am
Forum: Beginning OS Development
Topic: "Protected Mode" tutorial question
Replies: 3
Views: 8747

"Protected Mode" tutorial question

Hi, I am wondering, in the aforementioned tutorial, why you jmp 0x8:Stage2 . I am interested in the segment offset value, 0x8. I understand you explain that to be the offset in the GDT, but I had a look at the intel manual Vol 3A, Section 3.4.2, that the segment selector is actually a packed 16 bit ...
by scorpion007
Wed Jan 23, 2008 11:19 pm
Forum: Beginning OS Development
Topic: question about "Bootloaders 4"
Replies: 2
Views: 7495

Ah, I see.

Thanks for the explanation :)
by scorpion007
Wed Jan 23, 2008 6:00 am
Forum: Beginning OS Development
Topic: question about "Bootloaders 4"
Replies: 2
Views: 7495

question about "Bootloaders 4"

Hi,

I was looking in the code for this tute, namely the ReadSectors routine, and I was wondering why you always read 1 sector at a time, and loop, instead of passing the amount of sectors directly to AL?
by scorpion007
Sun Jan 20, 2008 9:28 am
Forum: Beginning OS Development
Topic: VESA
Replies: 11
Views: 20294

If the series reader demand for this is great enough, we might just skip the vga, and use VBE... What would you like? I don't know, I think if VGA is simpler I'd prefer it as a starting point, especially as it's supported on more platforms. 800x600 resolution is plenty for a start. If you like you ...
by scorpion007
Sun Nov 18, 2007 9:42 am
Forum: Beginning OS Development
Topic: Re: the tutorials (#6)
Replies: 8
Views: 14872

Re: the tutorials (#6)

In Tutorial 6, I was wondering why the bootloader sets org to 0, instead of 0x7c00, like you did previously? You execute a jmp to main right after it, but won't the code be missed, since the BIOS requires the starting code to be at 0x7c00? org 0 ; we will set regisers later start: jmp main ; jump to...