Search found 10 matches
- Wed Apr 07, 2010 3:06 am
- Forum: News Discussion
- Topic: Chapter 22: File Systems and the VFS
- Replies: 12
- Views: 86110
- Thu Mar 05, 2009 9:29 pm
- Forum: Beginning OS Development
- Topic: BootLoader 4
- Replies: 4
- Views: 15417
- Thu Mar 05, 2009 9:10 pm
- Forum: Beginning OS Development
- Topic: BootLoader 4
- Replies: 4
- Views: 15417
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 [...
- Thu Mar 05, 2009 8:06 am
- Forum: Beginning OS Development
- Topic: BootLoader 4
- Replies: 4
- Views: 15417
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 directory ...
- Wed Mar 04, 2009 9:08 pm
- Forum: Beginning OS Development
- Topic: BootLoader 3
- Replies: 7
- Views: 21837
- Wed Mar 04, 2009 8:48 am
- Forum: Beginning OS Development
- Topic: BootLoader 3
- Replies: 7
- Views: 21837
BootLoader 3
hi guys, It seems I'm making a habit of posting a topic for every tutorial I read 8). 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 ...
- Tue Mar 03, 2009 9:37 pm
- Forum: Beginning OS Development
- Topic: BootLoader 2
- Replies: 4
- Views: 15058
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...
- Tue Mar 03, 2009 8:23 pm
- Forum: Beginning OS Development
- Topic: BootLoader 2
- Replies: 4
- Views: 15058
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 ...
- Tue Mar 03, 2009 8:21 am
- Forum: Beginning OS Development
- Topic: BootLoader 2
- Replies: 4
- Views: 15058
BootLoader 2
hi,
I am going through tut 2, and there is something I want to make sure,
In the demo code, I see
Why do we need to set the data segment and extra segment address to 0? Is there any reason to it?
and the call what does it do?
Thanks you
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
and the call
Code: Select all
int 0x16
Thanks you
- Sat Feb 21, 2009 12:07 am
- Forum: Beginning OS Development
- Topic: Tutorial 19
- Replies: 14
- Views: 35078
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...