add comment / corrections
This commit is contained in:
Frater
parent
73ac87884a
commit
3a7382c761
8 changed files with 247 additions and 41 deletions
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@ -4,4 +4,4 @@ cd src
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"c:\program files\NASM\nasm" -f bin boot.asm -o ..\build\bios.bin
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cd ..
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qemu-system-x86_64 -bios build/bios.bin -device loader,file=build/vgabios.bin,addr=0xC0000,force-raw=on -device isa-debugcon,chardev=myconsole -chardev stdio,id=myconsole -k be -display sdl
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qemu-system-x86_64 -bios build/bios.bin -device loader,file=roms/vgabios.bin,addr=0xC0000,force-raw=on -device isa-debugcon,chardev=myconsole -chardev stdio,id=myconsole -k be -display sdl
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25
src/bda.asm
25
src/bda.asm
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@ -1,6 +1,31 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : bda.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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;
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; https://wiki.nox-rhea.org/back2root/ibm-pc-ms-dos/hardware/informations/bios_data_area
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;
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%define BDA_SEGMENT 0x0040 ; segment BDA
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; custom var
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61
src/boot.asm
61
src/boot.asm
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@ -1,37 +1,56 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : boot.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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BITS 16
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org 0
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; ---------------------------------------------------------------------------
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;
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; configuration du bios
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;
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; ---------------------------------------------------------------------------
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%define DEBUG_PORT 0xe9 ; 0x402 ou 0xe9
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%define VIDEO_SEG 0xB800 ; ou 0xB000
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%define VIDEO_ATTR 0x07
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; initial stack
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%define STACK_SEG 0x0030
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%define STACK_TOP 0x0100 ; choix commun en RAM basse (pile descend)
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%define STACK_SEG 0x0030 ; compatible avec le BMM (Bios Memory Maps)
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%define STACK_TOP 0x0100 ; choix commun en RAM basse (pile descendante)
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%define MEM_SEG_DEB 0x0800 ; 0x0800:0000 = 0x8000 (32KB) évite IVT/BDA + stack 7C00
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%define MEM_SEG_END 0xA000 ; 0xA000:0000 = 0xA0000 (début zone vidéo)
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%define MEM_SEG_STEP 0x0040 ; 1KB = 0x400 bytes = 0x40 paragraphs
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jmp reset ; ce jump n'est pas sensé être executer, il est présent uniquement pour le debug
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; definition du BDA
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%include ".\bda.asm"
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jmp reset
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%include ".\drivers\debug.asm"
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%include ".\drivers\gfx_cgam.asm"
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%include ".\drivers\mouse_ps2.asm"
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err_novga db 'No VGA Card BIOS',0
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err_vganok db 'VGA Not Initialized',0
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err_end db 'code completed successfully',0
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@ -74,10 +93,10 @@ endless: nop
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jmp endless
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; ---------------------------------------------------------------------------
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; Détection les ROM supplementaires
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; Teste la RAM de 0xC000 jusqu’à 0xE000, par pas de 2KB.
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; Test si le vecteur INT 10h à été modifié (par la ROM)
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;
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; Si une ROM est détectée, le code de la ROM sera appelé.
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; Si le vecteur n'a pas été modifiée, on considère que la ROM video n'a pas
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; été chargée.
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; ---------------------------------------------------------------------------
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setup_check_vga:
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; vérification de l'offset 0x0000:0x0040 qui DOIT etre différent de @default_isr
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@ -91,12 +110,11 @@ setup_check_vga:
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; Comparer avec default_isr (offset) et CS (segment)
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mov dx, default_isr ; DX = offset default_isr (dans notre CS)
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cmp bx, dx
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jne .init_ok ; interrupt different
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jne .init_ok ; vecteur different, bios initialisé
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cmp cx, ax
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jne .init_ok
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; no VGA init
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mov ax,cs
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mov ax,cs ; vecteur identique, sans doute pas d'initialisation
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mov ds,ax
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mov si, err_vganok
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@ -112,7 +130,6 @@ setup_check_vga:
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; ---------------------------------------------------------------------------
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setup_load_rom:
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mov bx, 0xC000
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mov al,'*'
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.scanloop:
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mov ds, bx
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cmp word[0x0000],0xAA55 ; ROM signature
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@ -133,20 +150,11 @@ setup_load_rom:
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add bx, 0x80 ; add 2kb
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cmp bx, 0xE000
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jbe .scanloop
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cmp al,'.'
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je .end
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; no rom found :
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mov bx,cs
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mov ds,bx
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mov si, err_novga
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call debug_puts
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.end:
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ret
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; ---------------------------------------------------------------------------
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; Détection RAM conventionnelle (8088, BIOS maison) — sans BIOS
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; Détection RAM conventionnelle
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; Teste la RAM de MEM_SEG_DEB jusqu’à 0xA000 (640KB), par pas de 1KB.
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; Méthode: sauvegarde 1 mot, écrit 2 patterns, relit, restaure.
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;
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@ -217,9 +225,6 @@ setup_ram:
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; ---------------------------------------------------------------------------
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; IVT install (8088, mode réel) - remplit les 256 vecteurs avec un handler IRET
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; Hypothèses:
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; - code en ROM (CS typiquement = 0xF000), handler réside dans ce même segment
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; - interruptions désactivées (CLI) pendant l'installation
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; ---------------------------------------------------------------------------
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setup_ivt:
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; installation de la table d'interrupts
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@ -1,4 +1,25 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : debug.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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debug_puts:
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.next:
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@ -1,3 +1,27 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : boot.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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%define GFX_MODE 0x06 ; MCGA HiRes (B/W)
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%define GFX_WIDTH 640
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%define GFX_HEIGHT 200
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@ -1,6 +1,31 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : gfx_cgam.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; graphics drivers for CGA 640x200x2
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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;
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; graphics drivers pour carte video/mode CGA-Mono (640x200x2)
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;
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%define VIDEO_SEG 0xB800 ; ou 0xB000
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%define GFX_MODE 0x06 ; MCGA HiRes (B/W)
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%define GFX_WIDTH 640
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%define GFX_HEIGHT 200
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@ -9,8 +34,12 @@
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%define CGA_ODD_BANK 0x2000
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%define BG16_SIZE 48
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; ce mode est entrelacé, un bit/pixel, 8 pixels par octet
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; ------------------------------------------------------------
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; initialise le mode graphique (via l'int 10h)
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;
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; ce mode est entrelacé, un bit/pixel, 8 pixels par octet
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; ------------------------------------------------------------
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gfx_init:
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; init graphics mode
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mov ah, 0x00 ; AH=00h set video mode
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@ -21,17 +50,72 @@ gfx_init:
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ret
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; PutPixel(x=cx, y=dx, color=al) sur page bh
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; ------------------------------------------------------------
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; Dessine un pixel, accès VRAM direct.
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;
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; In:
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; CX = x (0..639)
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; DX = y (0..199)
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; AL = color (0=black, !=0=white)
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;
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; ------------------------------------------------------------
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gfx_putpixel:
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mov ah, 0Ch
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;mov al, 0Fh ; couleur (0..15)
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;mov bh, 00h ; page
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;mov cx, 100 ; x
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;mov dx, 50 ; y
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int 10h
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push bx
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push di
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push es
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mov ax, VIDEO_SEG
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mov es, ax
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; DI = (y>>1)*80 + (x>>3) + (y&1)*0x2000
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mov bx, dx
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and bx, 1 ; BX = y&1
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mov ax, dx
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shr ax, 1 ; AX = y>>1
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mov di, ax
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mov ax, di
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mov di, CGA_STRIDE
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mul di ; DX:AX = (y>>1)*80
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mov di, ax
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test bx, 1
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jz .bank_ok
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add di, CGA_ODD_BANK
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.bank_ok:
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mov ax, cx
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shr ax, 3 ; AX = x>>3
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add di, ax
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; masque bit = 0x80 >> (x&7)
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mov bl, cl
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and bl, 7 ; BL = x&7
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mov ah, 080h
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mov cl, bl
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shr ah, cl ; AH = bitmask
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; write
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cmp al, 0
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je .clear
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.set:
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or byte [es:di], ah
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jmp .done
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.clear:
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not ah
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and byte [es:di], ah
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.done:
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pop es
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pop di
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pop bx
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ret
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; draw background pattern
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; ------------------------------------------------------------
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; Dessine un background "check-board", accès VRAM direct.
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;
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; ------------------------------------------------------------
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gfx_background:
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mov ax,VIDEO_SEG
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mov es,ax
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@ -1,5 +1,29 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : mouse_ps2.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; controlleur de souris via le i8042 (PC Classique)
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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||||
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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||||
;
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||||
; You should have received a copy of the GNU General Public License
|
||||
; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;
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; =============================================================================
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;
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; controleur de souris via le i8042 (PC Classique)
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;
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%define PS2_PORT_BUFFER 0x60
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@ -1,3 +1,26 @@
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; =============================================================================
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; Project : Custom BIOS / ROM
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; File : textmode.asm
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; Author : frater
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; Created : 06 jan 2026
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;
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; License : GNU General Public License v3.0 or later (GPL-3.0+)
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;
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; This program is free software: you can redistribute it and/or modify
|
||||
; it under the terms of the GNU General Public License as published by
|
||||
; the Free Software Foundation, either version 3 of the License, or
|
||||
; (at your option) any later version.
|
||||
;
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||||
; This program is distributed in the hope that it will be useful,
|
||||
; but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
; GNU General Public License for more details.
|
||||
;
|
||||
; You should have received a copy of the GNU General Public License
|
||||
; along with this program. If not, see <https://www.gnu.org/licenses/>.
|
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;
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; =============================================================================
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;
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; text mod functions
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;
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Reference in a new issue