????????????????????????????????????????????????A simple bootstrap
??????????????????????????????????????????????????????????????????? -----2004.11.1 (C) Gr1x
To make a long story short,and enough material can be found about the PC's POST procedure,?I'll just show my code and explain sth?important steps,I think my source code is self-explaining enough 'cause it's short and easy to understand?. I?have tested it with a floppy disk,? it's risky to test it with ur harddrive. If ?u did do it,I? am not responsible for any damage u made?: )
Environment?:(Window Platform)
?????a.VMWare(Optional).If u don't want to reboot ur system many times,u should get this.
?????b: Nasm.(Essential). As u need it to compile ur code . u may use Ndisasm as well to disassemble the plain binary code compiled.
????c:Visual C++ 6 or Visual Stdio .Net. As we have to write a EXE to write the bootstrap to floppy.
?????? U may use WinHex to write bootstrap to floppy too instead of this writing a programme.
1>Write the bootstrap procedure
----------------------------bootstrap.asm-------------------------------------------------
;***************************************************
;???????????????????? bootstrap.asm: 2004-11-1 (C) Gr1x
;?????????????????????Email:gr1x@sina.com
;****************************************************
[ORG 0]
?????jmp 07C0h:start??????????????? ; remember that BIOS loads?this procedure in ?0:7C00h,but don't count on registers like?DS
???????????????????????????????????????????? ;was initialized to 0. So we jump to it ourself.
????msg db 'Hello Gr1x!',0x0
start:
????; Update the segment registers
?????mov ax,cs
?????mov ds,ax
?????mov es,ax
?????mov si,msg ; Print msg
print:
?????lodsb ; loads charater at 0x7C0h:msg
?????mov ah,0eh ;?
?????int 10h
?????cmp al,0 ;
?????jne print ;?
?????jmp $
?????times 510-($-$$) db 0
?????dw 0000h??????? ;or dw 0AA55h,u can write anything here,it seems that BIOS doesn't check this 2 bytes when?
? ??????????????????????????; it try to boot from a floppy disk
-----------------------------------------------------------------------------------------------------
OK,now compile it:
????????>nasm bootstrap.asm -o bootstrap.bin
2.Now,copy this bootstrap to floppy's boot sector. If u do it with WinHex,u can omit following.
???I wrote a program which do this action.
------------------------------write_fd.cpp----------------------------------------------
//*********************************************
//??????????????write_fd.cpp: 2004-11-1 (C) Gr1x
//???????????????Email:gr1x@sian.com
//***********************************************
#include <windows.h>
#include <winioctl.h>
#include <stdio.h>
#pragma comment(linker,"/subsystem:console" )
void Banner()
{
?printf("---------------------------------------------/n");
?printf("? write_fd:write a file to floppy in raw mode/n");
?printf("? author:gr1x????????????? email:gr1x@sian.com/n");
?printf("? usage:write_fd filename/n");
?printf("---------------------------------------------/n);
}
int main(int argc,char **argv)
{
?HANDLE????????????????? hDevice=NULL,hFile=NULL;
?TCHAR?????????????????? szDevicename[64];
?LPTSTR????????????????? szBuff=NULL;
?DISK_GEOMETRY?????????? Geometry;
?BOOL??????????????????? bRet;
?DWORD?????????????????? bytes,bread,count;
?Banner();
?if(argc!=2)
?{
??printf("Usage:%s filename/n",*argv);
??exit(0);
?}
?__try
?{
??hFile=CreateFile(argv[1],GENERIC_READ,FILE_SHARE_READ,NULL,OPEN_EXISTING,NULL);
??if (hDevice == INVALID_HANDLE_VALUE)
??{
???printf("Error in open file %s!/n",argv[1]);
???__leave;
??}
??wsprintf(szDevicename,"////.//a:");
??hDevice = CreateFile( szDevicename,
???GENERIC_READ|GENERIC_WRITE,
???FILE_SHARE_READ|FILE_SHARE_WRITE,
???NULL,
???OPEN_EXISTING,
???0,
???NULL
???);
??if (hDevice == INVALID_HANDLE_VALUE)
??{
???printf("Error in open floppy device!");
???__leave;
??}
??DeviceIoControl(hDevice,FSCTL_LOCK_VOLUME,&count,NULL); ??DeviceIoControl(hDevice,IOCTL_DISK_GET_DRIVE_GEOMETRY,&Geometry,sizeof(DISK_GEOMETRY),NULL); ??szBuff = (LPSTR)HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,Geometry.BytesPerSector*2); ??if ( szBuff == NULL)??{???printf("Error in HeapAlloc!");???__leave;??} ??bytes = 512*2; ??bRet = ReadFile(hFile,szBuff,bytes,&bread,NULL); ??if (bRet==FALSE || bread<512)??{???printf("Error in read file!");???__leave;??} ??printf("%d bytes read from %s/n",argv[1]);??bRet=WriteFile(hDevice,NULL);??if (bRet==FALSE || bread<512)??{???printf("Error in write file to floppy!");???__leave;??} ??if(!DeviceIoControl(hDevice,FSCTL_UNLOCK_VOLUME,NULL))???printf("DeviceIoControl(hDevice,NULL) error!/n");??DeviceIoControl(hDevice,NULL); ??printf("Write finished!/nBoot sector in HEX:/n");??for(int j=0,int i=0; i<512; i++)??{???unsigned char ch=(unsigned char) szBuff[i];???if (j==8) printf(" -");???if (j==16)???{????printf("/n");????j=0;???}???j++;???if (ch<0x10) printf(" %2x",ch);???else printf(" %2x",ch);??}??printf("/n");?}?__finally?{??if(szBuff!=NULL)???HeapFree(GetProcessHeap(),HEAP_NO_SERIALIZE,szBuff);??if(hDevice!=NULL)???CloseHandle(hDevice);??if(hFile!=NULL)???CloseHandle(hFile);?}?return 0;}--------------------------------------------------------------------------------------------Don't ask me how to compile this cpp file!3>Type following commad in CMD????>write_fd bootstrap.bin4>OK,boot ur system with the floppy.God bless u!
