Make you're own OS

gooooogle · Post #1 (**permalink**) 03-15-2004, 08:05 AM

Well another of my strange interests is how things works and so I've been looking at the source code of a hello world operating system. The code is written in assembly and compiled using NASM.

Quote:

[BITS 16] ; 16 bit code generation
[ORG 0x7C00] ; Origin location

; Main program
main: ; Label for the start of the main program

mov ax,0x0000 ; Setup the Data Segment register
; Location of data is DS:Offset
mov ds,ax ; This can not be loaded directly it has to be in two steps.
; 'mov ds, 0x0000' will NOT work due to limitations on the CPU

mov si, HelloWorld ; Load the string into position for the procedure.
call PutStr ; Call/start the procedure

jmp $ ; Never ending loop

; Procedures
PutStr: ; Procedure label/start
; Set up the registers for the interrupt call
mov ah,0x0E ; The function to display a chacter (teletype)
mov bh,0x00 ; Page number
mov bl,0x07 ; Normal text attribute

.nextchar ; Internal label (needed to loop round for the next character)
lodsb ; I think of this as LOaD String Block
; (Not sure if thats the real meaning though)
; Loads [SI] into AL and increases SI by one
; Check for end of string '0'
or al,al ; Sets the zero flag if al = 0
; (OR outputs 0's where there is a zero bit in the register)
jz .return ; If the zero flag has been set go to the end of the procedure.
; Zero flag gets set when an instruction returns 0 as the answer.
int 0x10 ; Run the BIOS video interrupt
jmp .nextchar ; Loop back round tothe top
.return ; Label at the end to jump to when complete
ret ; Return to main program

; Data

HelloWorld db 'Saluton Mondo',13,10,0

; End Matter
times 510-($-$$) db 0 ; Fill the rest with zeros
dw 0xAA55 ; Boot loader signature

I've compiled and run this operating system from a diskette and it works. Although technically speaking this is only a bootloader and not a complete os as there is no actual kernel involved.

Note: Saluton Mondo is Hello World in esperanto.
Note Again: This code was written by Daniel Faulkner and is available at osdever.net.

BlackStorm · Post #2 (**permalink**) 03-15-2004, 08:11 AM

The only windows/app/exe code I can do is Delphi
Releasing a program today which was coded in Delphi actually

I have never looked at the source for a OS, mainly because I wouldnt understand other languages totally, some is simlar to delphi in ways though

gooooogle · Post #3 (**permalink**) 03-15-2004, 08:17 AM

Delphi uses the Pascal programming language does it not?

What program did you release?

If you know pascal this might be of interest
http://compilers.iecc.com/crenshaw/?the_id=64
Tells you how to build you're own compiler in Turbo Pascal.

BlackStorm · Post #4 (**permalink**) 03-15-2004, 08:44 AM

Yeah it uses pascal
Just released www.billvoice.com a few minutes ago

Will take a good while for it to get going I think, especially since this is the first beta.

I hate reading anything more than 2 pages long on the net so that guide would kill me hehe

gooooogle · Post #5 (**permalink**) 03-15-2004, 08:56 AM

If you also made hostingrefuge.com the forum for billvoice you will have one less forum to manage and people using the program might start posting under other topics as well.

Just a thought.

Leo · Post #6 (**permalink**) 03-17-2004, 05:02 AM

If its a commercial program I dont think that would be a good idea to mix it with here.
I think it would also add too many forums onto HostingRefuge.com if all forums from that forum on that site are added here.

Do you code gooooogle?

gooooogle · Post #7 (**permalink**) 03-17-2004, 07:17 AM

I'm learning to code. Currently looking at C ANSI and Python. But I'm c**p. The code above is from a web page I found.

imported_Stephen · Post #8 (**permalink**) 03-17-2004, 07:43 AM

Quote:

Currently looking at C ANSI and Python

Whats C ANSI?

What kind ofthings can you do using Python?
I have heard about it but never seen any code and dont know anything about it

Decker · Post #9 (**permalink**) 03-17-2004, 01:08 PM

Ah Assembly code, you made an old man happy :bow:

I came across an OS on one floppy a while ago, full blown GUI the lot - including a browser and mail client

I'll have to look that one out again - last time I tried it was on an old P1 166 laptop and it ran fine, wonder what it would do on my systems now :p

gooooogle · Post #10 (**permalink**) 03-17-2004, 01:22 PM

Quote:

Originally posted by Stephen
Whats C ANSI?

What kind ofthings can you do using Python?
I have heard about it but never seen any code and dont know anything about it

ANSI C is basicly C code that meets the requiremants of the ANSI standard. So in short it's normal everyday C.

Python is a programming language which is usually run through an interpreter. The language is very logic. A hello world program would be

Quote:

PRINT "Hello World"

while in ANSI C this would be

Quote:

#include <stdio.h>
main()
{
printf("Hello World/n");
}