hey yall,i recently wrote a boot loader in NASM now writing it in MASM v11 (i use the quick editor,ml with /AT and link16 with /TINY) proves to be challenging here is my code any help will be highly appriciated :)
.model TINY
.386
.code
org 7c00h //not sure
mov al,41h //character A
mov bh,0
mov cx,7 //number of times to print
mov ah,0Ah
int 10h
org 510 //this works
dw 0AA55h
end
you have to play tricks on the assembler to get the addresses to match
as a stand-alone file, it will be 512 bytes
in order for the linker to accept it as a tiny model program, the entry point has to be either 0 or 100h
but - when it is loaded into memory, it will be at 0000:7C00
one way to achieve this is to ORG 0, then use an offset to calculate the run-time addresses
if you use the forum search tool, you will find a few examples in the 16-bit sub-forum
by using the Advanced Search features, you can limit searches to that specific sub-forum, and search for "7C00"
also...
http://wiki.osdev.org/Expanded_Main_Page
they have a forum on the left pane
thanx :U dedndave i should have caught that one before i also came across a boot sector written in masm which is much easier to dissect.. that's after I've removed the unwanted portions:
.386 ; There are a couple 386+ opcodes.
_text SEGMENT PUBLIC USE16
assume CS:_text, DS:_text
org 0h
CRLF MACRO
mov ax, 0E0Dh
xor bx, bx
int 10h
mov al, 0Ah
int 10h
ENDM
PRINT MACRO var
pop dx
mov di, var
call printreg
mov ax, 0E20h
xor bx, bx
int 10h
ENDM
EntryPoint:
push sp
push ss
call NextLine ; get original IP+5 on the STACK
NextLine:
push cs
push es
push ds
push bp
push di
push si
push dx
push cx
push bx
push ax
; print a pretty message
mov ax, 1301h
mov bx, 0007h
mov cx, 23
mov dh, 10
mov dl, 1
push cs
pop es
mov bp, String
int 10h
CRLF
CRLF
; print the values of all the registers
PRINT _AX
PRINT _BX
PRINT _CX
PRINT _DX
CRLF
PRINT _SI
PRINT _DI
PRINT _BP
CRLF
PRINT _DS
PRINT _ES
CRLF
PRINT _CS
pop ax
sub ax, 5 ; ajust IP back five
push ax
PRINT _IP
PRINT _SS
PRINT _SP
CRLF
; make a little beep
mov ax, 0E07h
int 10h
; nothing else to do, so hang
hang:
jmp hang
; Big messy procedure that prints a three character string pointed to
; by DS:DI followed by the 16 bit hexidecimal number in DX.
printreg:
mov ah, 0Eh
xor bx, bx
mov al, byte ptr [di]
int 10h
mov al, byte ptr [di+1]
int 10h
mov al, byte ptr [di+2]
int 10h
xchg dl, dh
rol dl, 4
rol dh, 4
xor bx, bx
mov ah, 0Eh
mov cx, 4
ploop:
mov al, dl
and al, 0Fh
shr dx, 4
add al, '0'
cmp al, '9'
jbe nochange
add al, 'A' - '9'-1
nochange:
int 10h
loop ploop
RET
; Data Section.
;
; Notice that all the data pointers must have 7C00h added to it. This is
; because the bootsector is loaded to 0000:7C00h, so the base offset is
; 7C00h. However, the assembler thinks that the base offset is 0000h,
; so the 7C00h's are required to "fix-up" the base offest.
;
; Yes, there are many better ways of getting around this, but it's my code
; and I can do what I want! What's that about my attitude?
;
String = $ + 7C00h
db "initial register values"
_AX = $ + 7C00h
db "AX="
_BX = $ + 7C00h
db "BX="
_CX = $ + 7C00h
db "CX="
_DX = $ + 7C00h
db "DX="
_SI = $ + 7C00h
db "SI="
_DI = $ + 7C00h
db "DI="
_BP = $ + 7C00h
db "BP="
_SP = $ + 7C00h
db "SP="
_IP = $ + 7C00h
db "IP="
_CS = $ + 7C00h
db "CS="
_DS = $ + 7C00h
db "DS="
_ES = $ + 7C00h
db "ES="
_SS = $ + 7C00h
db "SS="
ORG 510 ; Make the file 512 bytes long
DW 0AA55h ; Add the boot signature
_text ENDS
END EntryPoint
i would make an equate at the beginning of the program
BOOT_OFS EQU 7C00h
then, when you load an address
mov si,offset _AX+BOOT_OFS
or, if you load a word...
mov ax,SomeWord+BOOT_OFS
nah....thats a long way which other way can i use just a couple of lines for the org 7c00h thats like the only hurdle
Quote from: akulamartin on March 19, 2012, 08:24:17 AM
hey yall,i recently wrote a boot loader in NASM now writing it in MASM v11 (i use the quick editor,ml with /AT and link16 with /TINY) proves to be challenging here is my code any help will be highly appriciated :)
I hope you realize, that we have a number of new members, who's requests match that of less than reputable purposes.
You indicated that this is a re-write of code. A post of the original code would be a good gesture on your part.
So please share with us, the original use/purpose of the NASM code for a boot loader ???
Then please share the need to cross code the project to MASM ???
So this is your opportunity, to share your need before the topic is locked for further discussion.
Regards, P1 :8)
@Micheal this is the boot sector(MASM) that gives me 32kb,i intent to have a skeleton for future projects:
.model TINY
.386
.code
org 7c00h //here is the issue
mov al,41h
mov bh,0
mov cx,7
mov ah,0Ah
int 10h
org 510
dw 0AA55h
end
what i want is similar code for the org 7c00h or an entire new code i've gone through the other sub forums but i still don't understand how to do the 0000:7c00 for the memory
The NASM version:
[BITS 16]
[ORG 0x7C00]
//my code here
JMP $
TIMES 510 - ($ - $$) db 0 ;fill the rest of sector with 0
DW 0xAA55
Since 7c00 can be 0000:7c00 or 07c0:0000, just make it 'org 0' (not really needed) and load segment 7c0 into ds/es.
they often make a segment "translation" by pushing a CS and label offset, then executing a RETF
@dendave,sinsi thanx guys but i prefer working examples kindly give me one using my code
here is some code i wrote a while back...
http://www.masm32.com/board/index.php?topic=12028.msg91657#msg91657
it demonstrates the segment translation as i mentioned above and is well commented
i will leave incorporation into your code up to you :P
Quote from: akulamartin on March 23, 2012, 11:49:17 AM@Micheal this is the boot sector(MASM) that gives me 32kb,i intent to have a skeleton for future projects:
Please give specific "
projects" that required a boot loaded.
I can tell you exactly why I had written a bootloader for myself, that was way back in MASM 5.0 day, completely legal copy, with the documentation.
Quote from: P1 on March 23, 2012, 04:01:27 AMSo please share with us, the original use/purpose of the NASM code for a boot loader ???
Another dodge by you, and I will assume the worst purpose here. Therefore lock the thread.
Quote from: Forum Rules3. Legality of content is not a negotiable matter in the forum. Assembler programming is mainstream programming and is primarily used by professional programmers who require the performance in specialised areas. Low level coding is both allowed and encouraged but there will be no viral or trojan technology allowed including technical data under the guise of AV technology, no cracking and similar activities in the guise of "Reverse Engineering", no hacking techniques or related technology and no support or help with or reference to pirated software. There will also be no links to pages that support or display any of these or any other illegal areas of coding.
We have a ZERO tolerance policy for virus writers.
Regards, P1 :8)
Quote from: P1 on March 23, 2012, 05:13:47 PM
Please give specific "projects" that required a boot loaded.
Regards, P1 :8)
it is very easy.
task1 - create the tool which offload dos or other os and transfer execution to boot other system
task2 - create program with native data exchange with some device
task3 - create program that uses particular modes of cpu
i think that creation of something is more intresting that virus writing
Is this a witch-hunt? Why is it dubious to translate a boot loader from NASM to MASM?
Writing a simple boot loader, is a common beginners task.
::) its for my kernel and i dont why im being grilled i just want a masm bootsector bcoz the nasm version was easier to work with ive seen this question 1000+ times so why is mine all of a sudden "virus/hacker" like??? is it the words im using?!
i think Michael simply misunderstood the direction you were headed
i wouldn't worry about it
continue on with the productive stuff :P
Quote from: dedndave on March 23, 2012, 03:21:30 PMhere is some code i wrote a while back...
http://www.masm32.com/board/index.php?topic=12028.msg91657#msg91657
it demonstrates the segment translation as i mentioned above and is well commented
i will leave incorporation into your code up to you :P
Quote from: P1 on March 23, 2012, 05:13:47 PM
Quote from: akulamartin on March 23, 2012, 11:49:17 AM@Micheal this is the boot sector(MASM) that gives me 32kb,i intent to have a skeleton for future projects:
Please give specific "projects" that required a boot loaded.
I can tell you exactly why I had written a bootloader for myself, that was way back in MASM 5.0 day, completely legal copy, with the documentation.Quote from: P1 on March 23, 2012, 04:01:27 AMSo please share with us, the original use/purpose of the NASM code for a boot loader ???
Another dodge by you, and I will assume the worst purpose here. Therefore lock the thread.Quote from: Forum Rules3. Legality of content is not a negotiable matter in the forum. Assembler programming is mainstream programming and is primarily used by professional programmers who require the performance in specialised areas. Low level coding is both allowed and encouraged but there will be no viral or trojan technology allowed including technical data under the guise of AV technology, no cracking and similar activities in the guise of "Reverse Engineering", no hacking techniques or related technology and no support or help with or reference to pirated software. There will also be no links to pages that support or display any of these or any other illegal areas of coding.
We have a ZERO tolerance policy for virus writers.
Regards, P1 :8)
what does a template(skeleton) do if i may ask???what if i want changes to my small operating system stage 1-2,new design,add features,port it to mobile,write it in C/C++,use visual studio 2010,2012,2030,20xx,use tasm etc
Quote from: qWord on March 23, 2012, 07:02:08 PM
Is this a witch-hunt? Why is it dubious to translate a boot loader from NASM to MASM?
Writing a simple boot loader, is a common beginners task.
i dont know i seem to draw a clash everywhere i go this is not something new anyway
Quote from: dedndave on March 23, 2012, 07:43:11 PM
i think Michael simply misunderstood the direction you were headed
i wouldn't worry about it
continue on with the productive stuff :P
Quote from: dedndave on March 23, 2012, 03:21:30 PMhere is some code i wrote a while back...
http://www.masm32.com/board/index.php?topic=12028.msg91657#msg91657
it demonstrates the segment translation as i mentioned above and is well commented
i will leave incorporation into your code up to you :P
aight lemme av a look at that n ama tap tha code fo show main rulez baybay!!!!
Quote from: akulamartin on March 23, 2012, 07:35:37 PM
::) its for my kernel and i dont why im being grilled i just want a masm bootsector bcoz the nasm version was easier to work with ive seen this question 1000+ times so why is mine all of a sudden "virus/hacker" like??? is it the words im using?!
After 9 posts and five days as a new member, you want us to believe you have seen this "
1000+ times", you have questions still ???
How many aliases does it take to "view" this question "
1000+ times", in how many other websites ???
So going from a more familiar assembler syntax(and more experience) to a less familiar assembler syntax makes sense to you ???
So why the dodge from the my original post ???
You want to to know how many times we stop hackers and virus writers ???
AGAIN, what is the purpose of the "
my kernel" code, that needs a boot loader ??? PLEASE NOTE: Your statement implies that "
my kernel" exists.
The video code was an example of kernel code programming ???
It seems that this hole is only being dug deeper here, with each round of questions.
Regards, P1 :8)
Quote from: qWord on March 23, 2012, 07:02:08 PMIs this a witch-hunt?
No, It is a "which" hunt. "Which" is the true purpose here.
Quote from: qWord on March 23, 2012, 07:02:08 PMWhy is it dubious to translate a boot loader from NASM to MASM?
Mismatch of skill, purpose and direction.
Quote from: qWord on March 23, 2012, 07:02:08 PMWriting a simple boot loader, is a common beginners task.
He claims to have written kernel code for this boot loader.
The posted code is missing common elements of "translated" boot loader. Do you not find this strange for a translation project, where the code syntax is mostly the same, it is the structure code surround that code is what he is asking about.
So he throws out a group of "A"s, for a video test, instead of a real message, like "Kernel loading ..." ???
But then again, I already know how tight a 512 byte boot loader is to code in is.
Regards, P1 :8)
Quote from: Rockphorr on March 23, 2012, 06:46:53 PMit is very easy.
task1 - create the tool which offload dos or other os and transfer execution to boot other system
task2 - create program with native data exchange with some device
task3 - create program that uses particular modes of cpu
i think that creation of something is more intresting that virus writing
I can think of more than that too.
It is not our place to put words into his mouth, let him speak for his self.
Truth is easy and quick to share.
Regards, P1 :8)
Quote from: akulamartin on March 23, 2012, 08:15:52 PMi dont know i seem to draw a clash everywhere i go this is not something new anyway
Good point !!!
So how many times has this happened before ???
There is lots of quality code already out there and you decide to start fresh here from "
where" ???
These are some of the mismatches, that just does not make sense to chase after for reason and purpose.
I am letting this play out for others to watch the process, of digging his own hole.
Regards, P1 :8)
Persistent.....so anyway dedndave im working on memory bit right now i'll post the code soon
akulamartin,
Tread with caution here, you have been given enough room to explain what you are doing and why but we have not yet heard an answer that makes sense. If you keep trying to feed us bullsh*t the topic will disappear and you will no longer be able to post here.
Just remember that the people you are dealing with have been around for many years writing complex code and they will not be fed bullsh*t. We have dealt with guys trying to write viruses and trojans for years and they only go one way, out the door.
i read the rules and wot i uploaded was free to modify and its another bootsector,does the code i wrote look like a virus...i dont think so it looks like a bootsector that doesnt work so i dont know wot the problem is when i ask for a solution, plus your estimation is way off...with your years of experience you can clearly see wot im asking for so i dont know where the virus bit is coming from it seems to me that theres some ego thing going on u cant really tell im writing virus u just assumed did i hint in anyway im writing a virus no...p1 needs to do his job i dont know wot issue he has wit me i dont know him u didnt find anything so u went all lawyer trapping you cant jus judge on words that a virus is being written or bcoz my ip changes i use my pc and i phone
I think something should be understood here,this is a programming site for learning assembler,and in its way a place for us older guys to hang out and talk to others in this line of programming. Something this site isn't is a democracy,this is Hutchs home that he has ALLOWED us to share. To allow ANY negative aspect with assembler,considering this is the WEB,could in fact cause this site to be tagged as something it is not. Heed Hutches words,he can and will do what he said,if even a hint of negative action is spotted.
It seems ive not been wanted here for sometime so anything i do is closely monitored even to an extent of "setup like questioning" i just came around to look fo an answer of how to write a bootsector in masm thats it,plain and simple if u feel im writing a virus,fine i know im not you can now remove me please.... :snooty:
Here is where I see the problem, one of our moderators asks a question about the intent of the code and the answer we got back was a pile of crap. If in fact what the question was about was writing a boot sector, we have a number of members who are very experienced at writing this type of code and as well, shifting to protected mode and other OS related tasks.
We are stuck with having had to deal with virus writers, hackers and trojan writers for years on end and as again, with a massive range of members experience we easily pick when someone is trying to feed us bullsh*t. If you are serious about writing a boot sector for a valid legal purpose then contact P1 and explain to him what you are doing and why you are doing it.
The problem for the forum admin and me in particular is any illegal posts eventually come back to me as the owner of the domain name that this forum runs under and i simply refuse to cover the arse of anyone who dumps any crap in here. While the forum protects the identity data of its members, if anyone dumps illegal content in here I will happily give them up to the Mossad, FBI, CIA, MI5, KGB, ASIO and even the penguins in Antarctica and actively assist them to find whoever has tried to dump illegal crap in here.