简单的hello world操作系统

; A Simple Hello World Operating System - Package ; =============================================== ; By Vivek Mohan ; Mail me : mailvivek27@sify.com ; My Home : http://www.geocities.com/cppresources/ ; ; The Package Includes ; 1. copyboot.cpp - boot sector copier ; 2. stripexe.cpp - exe header stripper ; 3. BOOT.ASM - the boot sector code ; 4. Readme - This file ; ; Minimum Requirements ; 1. TCC or DJGPP Dos Compilers ; 2. TASM for assembling BOOT.ASM , I am not sure wether it will ; assemble with other assemblers too. ; 3. A Floppy disk , only a fool would copy the boot sector into the hard ; disk. ; ; The Boot Sector ; =============== ; The boot sector of any disk is the first sector on the first head of the disk ; specifically (cylinder:0,head:0). When ever you switch on (or reset) the computer , ; the BIOS performs the power-on self test and then initializes its data. ; After this it checks the first sector of each disk usually in the order: ; floppy drives then primary disks (depending on the BIOS settings). ; When it finds a valid boot signature it loads the sector which ; consists of 512 bytes , to the memory at location 0:7C00. After this the boot sector ; code gets control. ; ; What does the boot sector code do ? ; =================================== ; The boot sector code can do anything. Usually boot sector code, loads the OS kernel ; and gives control to it. Here for example , it does nothing but print a message. ; ; What is the boot signature ? ; ============================ ; When the bios checks the first sector of all the disks it looks for a specific ; signature denoting a valid boot sector. This signature is 0AA55h located at the ; offset 510. Which means that the total size of the boot sector code is 512bytes (or ; 1 sector). ; ; So to make a valid boot sector , we must make sure that it is 512 bytes long ; and 0AA55h is present at the offset 510 (or 1FEh) and thats what is being done ; in BOOT.asm ; ; How do I build the Hello World OS ? ; =================================== ; ; Follow the below instructions carefully and you'll be running the Hello World OS ; in no time. ; ; 1. Compile and link the file copyboot.cpp to copyboot.exe ; 2. Compile and link the file stripexe.cpp to stripexe.exe ; 3. Assemble BOOT.ASM using TASM ; tasm boot.asm ; 4. Link the object file thus generated boot.obj ; tlink /x /3 boot.obj ; 5. Strip the header off the file boot.exe ; stripexe boot.exe boot.bin hdr.bin ; 6. Copy the boot sector code into a floppy ; copyboot boot.bin ; 7. Restart The Computer and see what happens... ; ; If you have any kind of problems please email me : mailvivek27@sify.com