Search found 10 matches

by Zig
Wed Apr 07, 2010 3:06 am
Forum: News Discussion
Topic: Chapter 22: File Systems and the VFS
Replies: 12
Views: 42120

Re: Chapter 22: File Systems and the VFS

Great :-)
by Zig
Thu Mar 05, 2009 9:29 pm
Forum: Beginning OS Development
Topic: BootLoader 4
Replies: 4
Views: 9029

:o as always, got it now. Thanks Andrew
by Zig
Thu Mar 05, 2009 9:10 pm
Forum: Beginning OS Development
Topic: BootLoader 4
Replies: 4
Views: 9029

Thanks Andrew, I was hoping you would answer I understand that we need to work out how many sector teh 2 FAT take up. I believe these do that mov al, BYTE [bpbNumberOfFATs] ; number of FATs mul WORD [bpbSectorsPerFAT] ; sectors used by FATs now the number of sector is stored in ax, add ax, WORD [bpb...
by Zig
Thu Mar 05, 2009 8:06 am
Forum: Beginning OS Development
Topic: BootLoader 4
Replies: 4
Views: 9029

BootLoader 4

hi guys, As I promised from the other post, here are questions for bootloader 4. 1. We're trying to get to the start of the root directory. And this is the piece of code Mike wrote LOAD_ROOT: ; compute size of root directory and store in "cx" xor cx, cx xor dx, dx mov ax, 0x0020 ; 32 byte ...
by Zig
Wed Mar 04, 2009 9:08 pm
Forum: Beginning OS Development
Topic: BootLoader 3
Replies: 7
Views: 12733

thanks again :)
by Zig
Wed Mar 04, 2009 8:48 am
Forum: Beginning OS Development
Topic: BootLoader 3
Replies: 7
Views: 12733

BootLoader 3

hi guys, It seems I'm making a habit of posting a topic for every tutorial I read . I have some questions for bootloader 3, could you guys help out? 1. I am trying out the demo for bootloader 3. I typed the code and try to compile to NASM, but I got an error because there are 2 [ORG] directive in th...
by Zig
Tue Mar 03, 2009 9:37 pm
Forum: Beginning OS Development
Topic: BootLoader 2
Replies: 4
Views: 8858

Hi, No - the segment address cant be anything other than 0 in this case. You quite correctly say that bpbOEM is 0x7C03 from the start of the segment. However, at the same time, the bootloader is loaded to the address 0x7C00 in physical memory, with the real bpbOEM being at 0x7C03 in physical memory...
by Zig
Tue Mar 03, 2009 8:23 pm
Forum: Beginning OS Development
Topic: BootLoader 2
Replies: 4
Views: 8858

thanks for the reply. I understand about the org directive. But could ds be any other value beside 0, say 1? We have bpbOEM is at 0x7C03 (and it is 8 byte long), the next one is 0x7C0B .... so the offset is 0x7C03 from the start of the segment, so does it matter what the segment address is? Because ...
by Zig
Tue Mar 03, 2009 8:21 am
Forum: Beginning OS Development
Topic: BootLoader 2
Replies: 4
Views: 8858

BootLoader 2

hi,

I am going through tut 2, and there is something I want to make sure,

In the demo code, I see

Code: Select all

   mov ds, ax      
   mov es, ax


Why do we need to set the data segment and extra segment address to 0? Is there any reason to it?

and the call

Code: Select all

int 0x16
what does it do?

Thanks you
by Zig
Sat Feb 21, 2009 12:07 am
Forum: Beginning OS Development
Topic: Tutorial 19
Replies: 14
Views: 20624

Well. Given the tutorials so far, you do have enough to make your own basic shell. You have keyboard input, memory management, console out, and access to the PIT. That is enough to make a calculator or a timer (or some strange combination of both). ~Andyhhp so are we going to talk about the shell a...