; almo7aya.asm · 7OS 0.8, a tiny real-mode operating system for almo7aya.dev ; ; build: npm run os (nasm + os/build.mjs, which also packs the filesystem) ; run: qemu-system-i386 -drive format=raw,file=public/os/almo7aya.img ; ; disk layout (512-byte sectors, LBA): ; 0 stage 1, the boot sector ; 1..31 stage 2, the kernel + shell (loaded at 0000:7E00) ; 32 7FS directory: 32 entries of 16 bytes ; 33.. file data, each file starts on a sector boundary ; ; what it does: ; - reads the disk geometry and loads files through INT 13h (LBA -> CHS by hand) ; - draws a colour console straight into VGA text memory at B800:0000 ; - hooks INT 1Ch (called by the BIOS timer interrupt, 18.2 Hz) for a live clock ; - "demo" switches to mode 13h, draws a plasma, writes with the BIOS font ROM ; (INT 10h AX=1130h) and animates by rotating the DAC palette, synced to vblank cpu 8086 bits 16 org 0x7C00 KERNEL_SECTORS equ 31 DIR_LBA equ 32 FILE_SEG equ 0x2000 ; files are loaded at 2000:0000 ; =================================================================== ; stage 1 · boot sector ; =================================================================== boot: cli xor ax, ax mov ds, ax mov es, ax mov ss, ax mov sp, 0x7C00 sti cld mov [boot_drive], dl mov si, s_loading call bputs mov ax, 0x0200 + KERNEL_SECTORS ; AH=02h read, AL=count mov cx, 0x0002 ; cylinder 0, sector 2 xor dh, dh mov dl, [boot_drive] mov bx, stage2 int 0x13 jc .fail jmp 0x0000:stage2 .fail: mov si, s_diskerr call bputs .halt: hlt jmp .halt bputs: lodsb test al, al jz .done mov ah, 0x0E xor bx, bx int 0x10 jmp bputs .done: ret boot_drive db 0x80 s_loading db "7OS: loading kernel...", 13, 10, 0 s_diskerr db "disk read error", 0 times 510-($-$$) db 0 dw 0xAA55 ; =================================================================== ; stage 2 · kernel, at 0000:7E00 ; =================================================================== COLOR equ 0x01 ; in strings: 0x01, attr A_TXT equ 0x07 A_HI equ 0x0F A_DIM equ 0x08 A_CYAN equ 0x0B A_YELLOW equ 0x0E A_GREEN equ 0x0A A_RED equ 0x0C A_BAR equ 0x1F A_BAR_HI equ 0x1E A_BAR_CYAN equ 0x1B %define C(a) COLOR, a stage2: call disk_init call hook_timer call screen_init mov si, s_boot call type_out call fs_count call print_dec mov si, s_boot2 call puts shell: mov si, s_prompt call puts call read_line call run_command jmp shell ; ------------------------------------------------------------------- ; disk: geometry from INT 13h/08h, LBA -> CHS, one sector at a time ; ------------------------------------------------------------------- spt dw 63 heads dw 16 disk_init: mov ah, 0x08 mov dl, [boot_drive] push es int 0x13 pop es jc .keep mov al, cl and ax, 0x003F jz .keep mov [spt], ax mov al, dh xor ah, ah inc ax mov [heads], ax .keep: ret ; AX = LBA, CX = count, ES:BX = buffer. CF set on error read_sectors: push ax push bx push cx push dx .next: push ax push cx xor dx, dx div word [spt] ; AX = LBA / spt, DX = LBA % spt mov cl, dl inc cl ; sectors count from 1 xor dx, dx div word [heads] ; AX = cylinder, DX = head mov ch, al ror ah, 1 ror ah, 1 and ah, 0xC0 or cl, ah ; cylinder bits 8-9 live in CL bits 6-7 mov dh, dl mov dl, [boot_drive] mov ax, 0x0201 int 0x13 pop cx pop ax jc .out add bx, 512 inc ax loop .next clc .out: pop dx pop cx pop bx pop ax ret ; ------------------------------------------------------------------- ; 7FS: a flat directory of 16-byte entries ; +0 name, 8.3 without the dot, space padded (11 bytes) ; +11 attribute (the colour dir uses) ; +12 start LBA (word) ; +14 size in bytes (word) ; ------------------------------------------------------------------- dirbuf times 512 db 0 dir_ok db 0 fs_load_dir: cmp byte [dir_ok], 1 je .ok mov ax, DIR_LBA mov cx, 1 mov bx, dirbuf call read_sectors jc .bad mov byte [dir_ok], 1 .ok: clc .bad: ret fs_count: ; AX = number of files call fs_load_dir xor ax, ax mov si, dirbuf .loop: cmp byte [si], 0 je .done inc ax add si, 16 cmp si, dirbuf + 512 jb .loop .done: ret ; DS:SI = 11-byte name. returns SI = entry, CF set if not found fs_find: push di push cx mov di, dirbuf .loop: cmp byte [di], 0 je .miss push si push di mov cx, 11 repe cmpsb pop di pop si je .hit add di, 16 cmp di, dirbuf + 512 jb .loop .miss: pop cx pop di stc ret .hit: mov si, di pop cx pop di clc ret ; SI = entry: loads the file to FILE_SEG:0000 and prints it, LF -> CR LF fsize dw 0 fs_type: push es mov ax, FILE_SEG mov es, ax mov cx, [si+14] mov [fsize], cx add cx, 511 mov cl, ch shr cl, 1 ; sectors = (size + 511) / 512 xor ch, ch mov ax, [si+12] xor bx, bx call read_sectors jc .err xor di, di mov cx, [fsize] jcxz .done .ch: mov al, [es:di] inc di cmp al, 13 je .skip cmp al, 10 jne .put mov al, 13 call putc mov al, 10 .put: call putc .skip: loop .ch .done: pop es ret .err: pop es mov si, s_ioerr jmp puts ; SI = "about.txt" -> fname = "ABOUT TXT" fname times 11 db ' ' make_83: push di mov di, fname mov cx, 11 mov al, ' ' rep stosb mov di, fname mov cx, 8 .base: lodsb test al, al jz .end cmp al, '.' je .ext jcxz .base ; names longer than 8: drop the rest call upper mov [di], al inc di dec cx jmp .base .ext: mov di, fname + 8 mov cx, 3 .e: lodsb test al, al jz .end call upper mov [di], al inc di loop .e .end: pop di ret upper: cmp al, 'a' jb .r cmp al, 'z' ja .r sub al, 'a' - 'A' .r: ret ; ------------------------------------------------------------------- ; timer: hook INT 1Ch, which the BIOS calls from IRQ0 18.2 times a second ; ------------------------------------------------------------------- old_1c dd 0 ticks dw 0 divider db 1 hook_timer: cli mov ax, [0x1C*4] mov [old_1c], ax mov ax, [0x1C*4+2] mov [old_1c+2], ax mov word [0x1C*4], clock_isr mov word [0x1C*4+2], 0 sti ret clock_isr: push ax push bx push cx push dx push di push ds push es xor ax, ax mov ds, ax ; our variables live in segment 0 inc word [ticks] dec byte [divider] jnz .chain mov byte [divider], 18 ; about once a second cmp byte [0x449], 3 ; only in text mode jne .chain mov ah, 0x02 ; RTC time, BCD int 0x1A jc .chain mov ax, 0xB800 mov es, ax mov di, 71 * 2 mov bh, A_BAR_HI mov al, ch call .bcd mov al, ':' call .chr mov al, cl call .bcd mov al, ':' call .chr mov al, dh call .bcd .chain: pushf ; chain to whoever had INT 1Ch before us call far [old_1c] pop es pop ds pop di pop dx pop cx pop bx pop ax iret .bcd: push ax shr al, 1 shr al, 1 shr al, 1 shr al, 1 add al, '0' call .chr pop ax and al, 0x0F add al, '0' .chr: mov ah, bh stosw ret ; ------------------------------------------------------------------- ; screen ; ------------------------------------------------------------------- row db 0 col db 0 attr db A_TXT fast db 0 screen_init: mov ax, 0x0003 ; 80x25 text, clears the screen int 0x10 call draw_header mov byte [row], 2 mov byte [col], 0 jmp sync_cursor draw_header: push es mov ax, 0xB800 mov es, ax xor di, di mov ax, (A_BAR << 8) | ' ' mov cx, 80 rep stosw xor di, di mov si, s_bar_left mov ah, A_BAR call .text mov di, 50 * 2 mov si, s_bar_gh mov ah, A_BAR_CYAN call .text pop es mov byte [divider], 1 ; draw the clock on the next tick ret .text: lodsb test al, al jz .ret stosw jmp .text .ret: ret putc: ; AL = character, colour from [attr] push ax push bx push di push es cmp al, 13 je .cr cmp al, 10 je .lf cmp al, 8 je .bs mov bx, 0xB800 mov es, bx call cell_offset mov ah, [attr] mov [es:di], ax inc byte [col] cmp byte [col], 80 jb .out .lf: mov byte [col], 0 inc byte [row] cmp byte [row], 25 jb .out call scroll jmp .out .cr: mov byte [col], 0 jmp .out .bs: cmp byte [col], 0 je .out dec byte [col] mov bx, 0xB800 mov es, bx call cell_offset mov word [es:di], (A_TXT << 8) | ' ' .out: call sync_cursor pop es pop di pop bx pop ax ret cell_offset: ; DI = (row * 80 + col) * 2 push ax mov al, [row] mov ah, 80 mul ah add al, [col] adc ah, 0 shl ax, 1 mov di, ax pop ax ret scroll: push ax push bx push cx push dx mov ax, 0x0601 ; scroll rows 1-24 up, keep the title bar mov bh, A_TXT mov cx, 0x0100 mov dx, 0x184F int 0x10 mov byte [row], 24 pop dx pop cx pop bx pop ax ret sync_cursor: push ax push bx push dx mov ah, 0x02 xor bh, bh mov dh, [row] mov dl, [col] int 0x10 pop dx pop bx pop ax ret puts: mov byte [fast], 1 jmp emit type_out: mov byte [fast], 0 emit: lodsb test al, al jz .done cmp al, COLOR jne .char lodsb mov [attr], al jmp emit .char: call putc cmp byte [fast], 0 jne emit call delay jmp emit .done: mov byte [attr], A_TXT ret delay: push ax ; ~12 ms per character, any key skips push cx push dx mov ah, 0x01 int 0x16 jz .wait mov byte [fast], 1 jmp .out .wait: mov ah, 0x86 xor cx, cx mov dx, 12000 int 0x15 .out: pop dx pop cx pop ax ret print_dec: ; AX, unsigned push ax push bx push cx push dx mov bx, 10 xor cx, cx .div: xor dx, dx div bx push dx inc cx test ax, ax jnz .div .out: pop ax add al, '0' call putc loop .out pop dx pop cx pop bx pop ax ret pad_dec: ; AX, right-aligned in 7 columns push ax push bx push cx push dx mov bx, 10 xor cx, cx .d: xor dx, dx div bx inc cx test ax, ax jnz .d mov bx, 7 sub bx, cx mov cx, bx .sp: mov al, ' ' call putc loop .sp pop dx pop cx pop bx pop ax jmp print_dec print_hex16: ; AX push ax mov al, ah call print_hex8 pop ax print_hex8: ; AL push ax shr al, 1 shr al, 1 shr al, 1 shr al, 1 call .nib pop ax .nib: push ax and al, 0x0F add al, '0' cmp al, '9' jbe .p add al, 7 .p: call putc pop ax ret put_bcd: push ax mov ah, al shr al, 1 shr al, 1 shr al, 1 shr al, 1 add al, '0' call putc mov al, ah and al, 0x0F add al, '0' call putc pop ax ret crlf: push ax mov al, 13 call putc mov al, 10 call putc pop ax ret put_n: lodsb ; CX characters from DS:SI call putc loop put_n ret ; ------------------------------------------------------------------- ; input ; ------------------------------------------------------------------- LINE_MAX equ 60 line times LINE_MAX+1 db 0 argp dw 0 ; first argument, or 0 read_line: xor cx, cx mov di, line .key: xor ah, ah int 0x16 cmp al, 13 je .enter cmp al, 8 je .back cmp al, ' ' jb .key cmp al, '~' ja .key cmp cx, LINE_MAX jae .key cmp al, 'A' jb .store cmp al, 'Z' ja .store add al, 'a' - 'A' .store: mov [di], al inc di inc cx mov byte [attr], A_HI call putc mov byte [attr], A_TXT jmp .key .back: jcxz .key dec di dec cx call putc jmp .key .enter: mov byte [di], 0 jmp crlf split_args: ; "cmd arg" -> line = "cmd", [argp] = "arg" mov word [argp], 0 mov si, line .sp: lodsb test al, al jz .r cmp al, ' ' jne .sp mov byte [si-1], 0 .skip: cmp byte [si], ' ' jne .set inc si jmp .skip .set: cmp byte [si], 0 je .r mov [argp], si .r: ret strcmp: push si push di .loop: mov al, [si] cmp al, [di] jne .out test al, al jz .out inc si inc di jmp .loop .out: pop di pop si ret ; ------------------------------------------------------------------- ; commands ; ------------------------------------------------------------------- run_command: call split_args cmp byte [line], 0 je .done mov bx, commands .next: mov di, [bx] test di, di jz .file mov si, line call strcmp je .found add bx, 4 jmp .next .found: call [bx+2] ret .file: mov si, line ; not a command: maybe a file, "about" = ABOUT.TXT call make_83 cmp byte [fname + 8], ' ' jne .try mov word [fname + 8], 'TX' mov byte [fname + 10], 'T' .try: call fs_load_dir mov si, fname call fs_find jc .nope jmp fs_type .nope: mov si, s_unknown1 call puts mov si, line call puts mov si, s_unknown2 call puts .done: ret commands: dw c_help, cmd_help dw c_dir, cmd_dir dw c_ls, cmd_dir dw c_type, cmd_type dw c_cat, cmd_type dw c_regs, cmd_regs dw c_ints, cmd_ints dw c_uptime, cmd_uptime dw c_time, cmd_time dw c_demo, cmd_demo dw c_ver, cmd_ver dw c_clear, cmd_clear dw c_cls, cmd_clear dw c_seven, cmd_seven dw c_panic, cmd_panic dw c_reboot, cmd_reboot dw 0 c_help db "help", 0 c_dir db "dir", 0 c_ls db "ls", 0 c_type db "type", 0 c_cat db "cat", 0 c_regs db "regs", 0 c_ints db "ints", 0 c_uptime db "uptime", 0 c_time db "time", 0 c_demo db "demo", 0 c_ver db "ver", 0 c_clear db "clear", 0 c_cls db "cls", 0 c_seven db "7", 0 c_panic db "panic", 0 c_reboot db "reboot", 0 cmd_help: mov si, s_help jmp puts cmd_ver: mov si, s_ver jmp puts cmd_seven: mov si, s_seven jmp puts cmd_dir: call fs_load_dir jc .err mov si, s_dirhead call puts mov bx, dirbuf xor dx, dx ; total bytes .ent: cmp byte [bx], 0 je .end mov al, [bx+11] mov [attr], al mov si, bx mov cx, 8 call put_n mov al, ' ' call putc mov cx, 3 call put_n mov byte [attr], A_TXT mov ax, [bx+14] add dx, ax call pad_dec mov si, s_lba call puts mov ax, [bx+12] call print_dec call crlf add bx, 16 cmp bx, dirbuf + 512 jb .ent .end: mov si, s_dirfoot call puts call fs_count call print_dec mov si, s_files call puts mov ax, dx call print_dec mov si, s_bytes jmp puts .err: mov si, s_ioerr jmp puts cmd_type: mov si, [argp] test si, si jz .usage call make_83 call fs_load_dir mov si, fname call fs_find jc .nf jmp fs_type .usage: mov si, s_typeuse jmp puts .nf: mov si, s_notfound jmp puts cmd_regs: ; the registers as the shell sees them pushf push ss push es push ds push cs push sp push bp push di push si push dx push cx push bx push ax mov si, s_regnames mov cx, 13 .r: mov byte [attr], A_CYAN lodsb call putc lodsb call putc mov byte [attr], A_DIM mov al, '=' call putc mov byte [attr], A_HI pop ax call print_hex16 mov byte [attr], A_TXT mov al, ' ' call putc cmp cx, 6 ; break the line after SP jne .n call crlf .n: loop .r jmp crlf cmd_ints: mov di, int_list .i: mov al, [di] inc di cmp al, 0xFF je .done mov [cur_int], al mov si, s_int call puts mov byte [attr], A_CYAN mov al, [cur_int] call print_hex8 mov si, s_arrow call puts xor bh, bh mov bl, [cur_int] shl bx, 1 shl bx, 1 mov byte [attr], A_HI mov ax, [bx+2] call print_hex16 mov al, ':' call putc mov ax, [bx] call print_hex16 cmp word [bx+2], 0 jne .rom mov si, s_hooked call puts jmp .nl .rom: mov si, s_rom call puts .nl: call crlf jmp .i .done: ret cur_int db 0 int_list db 0x08, 0x10, 0x13, 0x16, 0x1A, 0x1C, 0xFF cmd_uptime: mov si, s_up call puts mov ax, [ticks] xor dx, dx mov bx, 18 div bx call print_dec mov si, s_up2 call puts mov ax, [ticks] call print_dec mov si, s_up3 jmp puts cmd_time: mov ah, 0x02 int 0x1A jc .none push dx push cx mov si, s_time call puts pop cx mov al, ch call put_bcd mov al, ':' call putc mov al, cl call put_bcd mov al, ':' call putc pop dx mov al, dh call put_bcd jmp crlf .none: mov si, s_notime jmp puts cmd_clear: mov ax, 0x0600 mov bh, A_TXT mov cx, 0x0100 mov dx, 0x184F int 0x10 mov byte [row], 1 mov byte [col], 0 jmp sync_cursor cmd_panic: mov si, s_panic call puts db 0x0F, 0x0B ; ud2: invalid opcode, on purpose cli .hang: hlt jmp .hang cmd_reboot: mov si, s_reboot call puts int 0x19 ; ------------------------------------------------------------------- ; demo: mode 13h plasma + palette rotation ; ------------------------------------------------------------------- font_off dw 0 font_seg dw 0 shift db 0 scale db 1 cmd_demo: push es push bp mov ax, 0x1130 ; INT 10h/1130h: where is the 8x16 font? ES:BP mov bh, 0x06 int 0x10 mov [font_off], bp mov [font_seg], es pop bp pop es mov ax, 0x0013 ; 320x200, 256 colours, A000:0000 int 0x10 push es mov ax, 0xA000 mov es, ax ; plasma: c = sin[x] + sin[2y] + sin[x+y] + sin[(x-y)/2], each 0..63 xor di, di xor dx, dx ; y .row: xor cx, cx ; x .px: mov bx, cx and bx, 0xFF mov al, [sine + bx] mov bx, dx shl bx, 1 and bx, 0xFF add al, [sine + bx] mov bx, cx add bx, dx and bx, 0xFF add al, [sine + bx] mov bx, cx sub bx, dx sar bx, 1 and bx, 0xFF add al, [sine + bx] stosb ; 0..252, colour 255 stays for text inc cx cmp cx, 320 jb .px inc dx cmp dx, 200 jb .row mov si, s_demo_big ; written with the BIOS font ROM at 4x mov bx, 32 mov dx, 50 mov byte [scale], 4 call draw_text mov byte [scale], 1 mov si, s_demo_small mov bx, 64 mov dx, 140 call draw_text mov si, s_demo_key mov bx, 108 mov dx, 172 call draw_text mov dx, 0x3C8 ; DAC colour 255 = white mov al, 255 out dx, al inc dx mov al, 63 out dx, al out dx, al out dx, al .frame: call vsync call set_palette inc byte [shift] mov ah, 0x01 ; any key ends it int 0x16 jz .frame xor ah, ah int 0x16 pop es call screen_init mov si, s_demo_bye jmp puts vsync: mov dx, 0x3DA ; wait for the start of vertical retrace .a: in al, dx test al, 8 jnz .a .b: in al, dx test al, 8 jz .b ret set_palette: ; DAC colours 0..254 from the sine, rotated mov dx, 0x3C8 xor al, al out dx, al inc dx xor cx, cx xor bh, bh .c: mov bl, cl add bl, [shift] mov al, [sine + bx] out dx, al ; red add bl, 85 mov al, [sine + bx] shr al, 1 out dx, al ; green add bl, 85 mov al, [sine + bx] out dx, al ; blue inc cx cmp cx, 255 jb .c ret ; SI = text, BX = x, DX = y, colour 255, ES = A000 draw_text: .ch: lodsb test al, al jz .done push si push ds push dx xor ah, ah mov cl, 4 shl ax, cl ; char * 16 mov si, [font_off] add si, ax mov ds, [font_seg] mov cx, 16 .glyph: mov ah, [si] inc si push cx push bx mov cx, 8 .bit: shl ah, 1 jnc .skip call block .skip: add bl, [cs:scale] adc bh, 0 loop .bit pop bx pop cx add dl, [cs:scale] adc dh, 0 loop .glyph pop dx pop ds pop si mov al, [scale] xor ah, ah mov cl, 3 shl ax, cl ; x += 8 * scale add bx, ax jmp .ch .done: ret block: ; scale x scale pixels of colour 255 at (BX, DX) push ax push cx push dx push di mov ax, 320 mul dx add ax, bx mov di, ax mov cl, [cs:scale] xor ch, ch .y: push cx push di mov cl, [cs:scale] mov al, 255 rep stosb pop di pop cx add di, 320 loop .y pop di pop dx pop cx pop ax ret sine: ; 256 bytes, 0..63, written by build.mjs %include "sine.inc" ; ------------------------------------------------------------------- ; text ; ------------------------------------------------------------------- s_bar_left db " 7OS 0.8 ", 0xB3, " Ali Almohaya ", 0xB3, " Staff Web Engineer", 0 s_bar_gh db "github.com/Almo7aya", 0 s_boot db C(A_DIM), "7OS 0.8 ", 0xFA, " 8086 real mode ", 0xFA, " kernel at 0000:7E00 ", 0xFA, " INT 1Ch hooked", 13, 10, 13, 10 db C(A_HI), "Ali Almohaya (Almo", C(A_YELLOW), "7", C(A_HI), "aya)", 13, 10 db C(A_TXT), "Staff Web Engineer @ Anghami & OSN+", 13, 10 db "Web and smart-TV streaming apps, with a soft spot for video playback and DRM.", 13, 10 db "Beyond the web: low-level code, emulation and C++, just for the fun of it.", 13, 10 db "Yemen ", 0x1A, " Riyadh", 13, 10 db C(A_CYAN), "github.com/Almo", C(A_YELLOW), "7", C(A_CYAN), "aya", 13, 10, 13, 10 db C(A_DIM), "7FS mounted from LBA 32: ", C(A_HI), 0 s_boot2 db C(A_DIM), " files. try ", C(A_HI), "help", C(A_DIM), ", ", C(A_HI), "dir", C(A_DIM), " or ", C(A_HI), "demo", 13, 10, 0 s_prompt db C(A_YELLOW), "almo7aya", C(A_DIM), "> ", 0 s_unknown1 db C(A_RED), "unknown command: ", C(A_TXT), 0 s_unknown2 db C(A_DIM), " (try help)", 13, 10, 0 s_ioerr db C(A_RED), "disk read error", 13, 10, 0 s_notfound db C(A_RED), "file not found", C(A_DIM), " (try dir)", 13, 10, 0 s_typeuse db C(A_DIM), "usage: type FILE.TXT", 13, 10, 0 s_help db C(A_HI), "commands", 13, 10 db C(A_CYAN), " dir ", C(A_TXT), "list the files on the 7FS disk", 13, 10 db C(A_CYAN), " type FILE ", C(A_TXT), "print a file, or just type its name: about, work...", 13, 10 db C(A_CYAN), " demo ", C(A_TXT), "mode 13h plasma, palette rotation, font ROM", 13, 10 db C(A_CYAN), " regs ", C(A_TXT), "dump the CPU registers", 13, 10 db C(A_CYAN), " ints ", C(A_TXT), "show the interrupt vector table", 13, 10 db C(A_CYAN), " uptime ", C(A_TXT), "timer ticks since boot (INT 1Ch)", 13, 10 db C(A_CYAN), " time ", C(A_TXT), "read the real-time clock (INT 1Ah)", 13, 10 db C(A_CYAN), " ver clear 7 panic reboot", 13, 10, 0 s_dirhead db C(A_DIM), " Volume in drive C is 7OS", 13, 10, " Directory of C:\", 13, 10, 13, 10, 0 s_dirfoot db C(A_DIM), " ", 0 s_lba db C(A_DIM), " LBA ", 0 s_files db C(A_DIM), " file(s) ", 0 s_bytes db C(A_DIM), " bytes", 13, 10, 0 s_regnames db "AXBXCXDXSIDIBPSPCSDSESSSFL" s_int db C(A_DIM), " INT ", 0 s_arrow db C(A_DIM), "h -> ", 0 s_hooked db C(A_YELLOW), " hooked by 7OS", 0 s_rom db C(A_DIM), " BIOS ROM", 0 s_up db C(A_DIM), "up ", C(A_HI), 0 s_up2 db C(A_DIM), " s (", C(A_HI), 0 s_up3 db C(A_DIM), " ticks of IRQ0 at 18.2 Hz)", 13, 10, 0 s_ver db "7OS 0.8 ", 0xFA, " 8086 real mode ", 0xFA, " NASM ", 0xFA, " 7FS ", 0xFA, " github.com/Almo7aya", 13, 10, 0 s_time db C(A_DIM), "RTC ", C(A_HI), 0 s_notime db "no real-time clock", 13, 10, 0 s_reboot db C(A_DIM), "INT 19h...", 13, 10, 0 s_demo_big db "ALMO7AYA", 0 s_demo_small db "7OS ", 0xFA, " MODE 13H ", 0xFA, " 8086", 0 s_demo_key db "PRESS ANY KEY", 0 s_demo_bye db C(A_DIM), "back in text mode 03h", 13, 10, 0 s_seven db C(A_YELLOW) db " ", 0xDB, 0xDB, 0xDB, 0xDB, 0xDB, 0xDB, 0xDB, 0xDB, 13, 10 db " ", 0xDB, 0xDB, 13, 10 db " ", 0xDB, 0xDB, 13, 10 db " ", 0xDB, 0xDB, 13, 10 db " ", 0xDB, 0xDB, 13, 10, 0 s_panic db 13, 10, C(A_RED), "Kernel panic - not syncing: user typed 'panic'", 13, 10 db C(A_DIM), "executing UD2. real hardware hangs here.", 13, 10, 0 kernel_end: times (KERNEL_SECTORS * 512) - (kernel_end - stage2) db 0 ; fails to build if the kernel outgrows its sectors