04. November 2025, 05:46
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[BITS 16]
org 0x7C00
start:
mov [bootdrv], dl
mov ax, cs
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
; -----------------------------------
; Setup Stack
; -----------------------------------
cli ; Keine Interrupts!
mov ax, 0x9000 ; Stackadresse
mov ss, ax ; SS = 9000 (unser Stack)
mov sp, 0 ; SP = 0000 (der Stackpointer)
sti ; Interrupts zulassen
; -----------------------------------
; Enable A20
; -----------------------------------
call enableA20
; -----------------------------------
; Load Kernel
; -----------------------------------
%include "load_floppy.inc"
; -----------------------------------
; Print a message
; -----------------------------------
%include "message.inc" <-----------------------HIER DIESE MESSAGE WIRD NICH ANGEZEIGT (ES SEI DENN ICH MACHE SIE VOR DEN FLOPPY LOAD)
; -----------------------------------
; Setup GDT
; -----------------------------------
lgdt [gdt]
; -----------------------------------
; Enter Protected Mode
; -----------------------------------
cli
mov ecx, CR0
or ecx, 1
mov CR0, ecx
db 0xea ;Bitmuster für einen FAR JUMP
dw PMode ;Angabe des Offsets zu dem gesprungen werden soll
dw 0x8 ;Angabe des Selektors für das Segment zu dem gesprungen werden soll.
; -----------------------------------
; Refresh Registers
; -----------------------------------
[BITS 32]
PMode:
mov eax, 2 ;Index 2 der GDT auswählen
shl eax, 3
mov ds, ax
mov es, ax
mov ss, ax
mov eax, 0
mov fs, ax ;FS und GS auf NULL Deskriptor zeigen lassen
mov gs, ax
mov esp, 0x1FFFF ;ESP setzen
; -----------------------------------
; Jump to the Kernel
; -----------------------------------
jmp dword 8:0x10000
%include "gdt.inc"
%include "a20gate.inc"
bootdrv db 0
loadmsg db "Loading ClusterOS...",13,10,0
TIMES 510-($-$$) DB 0
SIGNATURE DW 0xAA55
_disk_reset:
; Diskdrive reset (Interrupt 13h, 0)
push ds ; Sichere DS
mov ax, 0 ; Die gewünschte Funktion (reset)
mov dl, [bootdrv]
int 13h ; Den Interrupt ausführen
pop ds ; DS wiederherstellen
jc _disk_reset ; Geht nicht? -> Noch mal!
; ------------------------------------------------
; kernel
; ------------------------------------------------
_loadkernel:
mov ax,0x1000 ; ES:BX = 10000
mov es,ax
mov bx, 0
mov al, 18 ; num of sectors
mov cx, 2 ; cylinder + start sector
mov dh, 0 ; head
; Read Sectors( Int 0x13, 2 )
mov dl, [bootdrv]
mov ah, 2
int 0x13
jc _loadkernel
_loadprogramfiles:
; ------------------------------------------------
; command
; ------------------------------------------------
_loadprogramfiles_1:
mov ax,0x5200 ; ES:BX = 52000
mov es,ax
mov bx, 0
mov al, 18 ; num of sectors
mov cx, 2 ; cylinder + start sector
mov dh, 1 ; head
; Read Sectors( Int 0x13, 2 )
mov dl, [bootdrv]
mov ah, 2
int 0x13
jc _loadprogramfiles_1 ; Fehler? Noch mal!
; ------------------------------------------------
; info
; ------------------------------------------------
_loadprogramfiles_2:
mov ax,0x5300 ; ES:BX = 53000
mov es,ax
mov bx, 0
mov al, 18 ; num of sectors
mov cx, 5 ; cylinder + start sector
mov dh, 1 ; head
; Read Sectors( Int 0x13, 2 )
mov dl, [bootdrv]
mov ah, 2
int 0x13
jc _loadprogramfiles_2 ; Fehler? Noch mal!
_load_end:
; deactivate floppy-motor
mov dx,0x3F2
mov al,0x0C
out dx,al
mov si,loadmsg
putstr:
lodsb ; Byte laden
or al,al
jz short putstrd ; 0-Byte? -> Ende!
mov ah,0x0E ; Funktion 0x0E
mov bx,0x0007 ; Attribut-Byte (wird nicht benötigt)
int 0x10 ; schreiben
jmp putstr ; Nächstes Byte
putstrd:
gdt_start:
dd 0 ;Ein DWORD mit dem Wert 0
dd 0 ;Ein DWORD mit dem Wert 0
FLAT_CODE: ; 1
dw 0xFFFFF
dw 0x0
db 0x0
db 9Ah
db 0CFh
db 0
FLAT_DATA: ; 2
dw 0xFFFFF
dw 0x0
db 0x0
db 92h
db 0CFh
db 0
gdt:
dw gdt - gdt_start - 1
dd gdt_start
;;
;; enableA20.s (adapted from Visopsys OS-loader)
;;
;; Copyright (c) 2000, J. Andrew McLaughlin
;; You're free to use this code in any manner you like, as long as this
;; notice is included (and you give credit where it is due), and as long
;; as you understand and accept that it comes with NO WARRANTY OF ANY KIND.
;; Contact me at jamesamc@yahoo.com about any bugs or problems.
;;
enableA20:
;; This subroutine will enable the A20 address line in the keyboard
;; controller. Takes no arguments. Returns 0 in EAX on success,
;; -1 on failure. Written for use in 16-bit code, see lines marked
;; with 32-BIT for use in 32-bit code.
pusha
;; Make sure interrupts are disabled
cli
;; Keep a counter so that we can make up to 5 attempts to turn
;; on A20 if necessary
mov CX, 5
.startAttempt1:
;; Wait for the controller to be ready for a command
.commandWait1:
xor AX, AX
in AL, 64h
bt AX, 1
jc .commandWait1
;; Tell the controller we want to read the current status.
;; Send the command D0h: read output port.
mov AL, 0D0h
out 64h, AL
;; Wait for the controller to be ready with a byte of data
.dataWait1:
xor AX, AX
in AL, 64h
bt AX, 0
jnc .dataWait1
;; Read the current port status from port 60h
xor AX, AX
in AL, 60h
;; Save the current value of (E)AX
push AX; 16-BIT
;; push EAX; 32-BIT
;; Wait for the controller to be ready for a command
.commandWait2:
in AL, 64h
bt AX, 1
jc .commandWait2
;; Tell the controller we want to write the status byte again
mov AL, 0D1h
out 64h, AL
;; Wait for the controller to be ready for the data
.commandWait3:
xor AX, AX
in AL, 64h
bt AX, 1
jc .commandWait3
;; Write the new value to port 60h. Remember we saved the old
;; value on the stack
pop AX; 16-BIT
;; pop EAX; 32-BIT
;; Turn on the A20 enable bit
or AL, 00000010b
out 60h, AL
;; Finally, we will attempt to read back the A20 status
;; to ensure it was enabled.
;; Wait for the controller to be ready for a command
.commandWait4:
xor AX, AX
in AL, 64h
bt AX, 1
jc .commandWait4
;; Send the command D0h: read output port.
mov AL, 0D0h
out 64h, AL
;; Wait for the controller to be ready with a byte of data
.dataWait2:
xor AX, AX
in AL, 64h
bt AX, 0
jnc .dataWait2
;; Read the current port status from port 60h
xor AX, AX
in AL, 60h
;; Is A20 enabled?
bt AX, 1
;; Check the result. If carry is on, A20 is on.
jc .success
;; Should we retry the operation? If the counter value in ECX
;; has not reached zero, we will retry
loop .startAttempt1
;; Well, our initial attempt to set A20 has failed. Now we will
;; try a backup method (which is supposedly not supported on many
;; chipsets, but which seems to be the only method that works on
;; other chipsets).
;; Keep a counter so that we can make up to 5 attempts to turn
;; on A20 if necessary
mov CX, 5
.startAttempt2:
;; Wait for the keyboard to be ready for another command
.commandWait6:
xor AX, AX
in AL, 64h
bt AX, 1
jc .commandWait6
;; Tell the controller we want to turn on A20
mov AL, 0DFh
out 64h, AL
;; Again, we will attempt to read back the A20 status
;; to ensure it was enabled.
;; Wait for the controller to be ready for a command
.commandWait7:
xor AX, AX
in AL, 64h
bt AX, 1
jc .commandWait7
;; Send the command D0h: read output port.
mov AL, 0D0h
out 64h, AL
;; Wait for the controller to be ready with a byte of data
.dataWait3:
xor AX, AX
in AL, 64h
bt AX, 0
jnc .dataWait3
;; Read the current port status from port 60h
xor AX, AX
in AL, 60h
;; Is A20 enabled?
bt AX, 1
;; Check the result. If carry is on, A20 is on, but we might warn
;; that we had to use this alternate method
jc .warn
;; Should we retry the operation? If the counter value in ECX
;; has not reached zero, we will retry
loop .startAttempt2
;; OK, we weren't able to set the A20 address line. Do you want
;; to put an error message here?
jmp .fail
.warn:
;; Here you may or may not want to print a warning message about
;; the fact that we had to use the nonstandard alternate enabling
;; method
.success:
sti
popa
xor EAX, EAX
ret
.fail:
sti
popa
mov EAX, -1
ret
_disk_reset:
; Diskdrive reset (Interrupt 13h, 0)
push ds ; Sichere DS
mov ax, 0 ; Die gewünschte Funktion (reset)
mov dl, [bootdrv]
int 13h ; Den Interrupt ausführen
pop ds ; DS wiederherstellen
jc _disk_reset ; Geht nicht? -> Noch mal!
; ------------------------------------------------
; kernel
; ------------------------------------------------
_loadkernel:
mov ax,0x1000 ; ES:BX = 10000
mov es,ax
mov bx, 0
mov al, 18 ; num of sectors
mov cx, 2 ; cylinder + start sector
mov dh, 0 ; head
; Read Sectors( Int 0x13, 2 )
mov dl, [bootdrv]
mov ah, 2
int 0x13
jc _loadkernel
_loadprogramfiles:
; ------------------------------------------------
; command
; ------------------------------------------------
_loadprogramfiles_1:
mov ax,0x5200 ; ES:BX = 52000
mov es,ax
mov bx, 0
mov al, 18 ; num of sectors
mov cx, 2 ; cylinder + start sector
mov dh, 1 ; head
; Read Sectors( Int 0x13, 2 )
mov dl, [bootdrv]
mov ah, 2
int 0x13
jc _loadprogramfiles_1 ; Fehler? Noch mal!
; ------------------------------------------------
; info
; ------------------------------------------------
_loadprogramfiles_2:
mov ax,0x5300 ; ES:BX = 53000
mov es,ax
mov bx, 0
mov al, 18 ; num of sectors
mov cx, 5 ; cylinder + start sector
mov dh, 1 ; head
; Read Sectors( Int 0x13, 2 )
mov dl, [bootdrv]
mov ah, 2
int 0x13
jc _loadprogramfiles_2 ; Fehler? Noch mal!
_load_end:
