The Third 512-byte OS Contest!

Masterkiller · **Joined:** Sat May 05, 2007 6:20 pm **Posts:** 153

Coddy wrote:

well, when I disassembled it I got a total of 33 lines of ??? so I am guessing that meens it does not know

It seems the code is 0xF5 (245) bytes. The rest are strings and probably the melody itself

Quite impressive!
P.S. He sets ES to 0, not using it as 0, then sets it to 0xB800 for video memory. Suppressing MOV ES, ax where ax=0 will free 2 more bytes

Code:

seg000:0000 ;
seg000:0000 ; ã=========================================================================¬
seg000:0000 ; ¦ This file is generated by The Interactive Disassembler (IDA) ¦
seg000:0000 ; ¦ Copyright (c) 2006 by DataRescue sa/nv, <[email protected]> ¦
seg000:0000 ; ¦ Licensed to: Freeware version ¦
seg000:0000 ; L=========================================================================-
seg000:0000 ;
seg000:0000 ; ---------------------------------------------------------------------------
seg000:0000 ; File Name : C:\512OS\1.bin
seg000:0000 ; Format : Binary file
seg000:0000 ; Base Address: 0000h Range: 0000h - 0200h Loaded length: 0200h
seg000:0000
seg000:0000 .686p
seg000:0000 .mmx
seg000:0000 .model flat
seg000:0000
seg000:0000 ; ===========================================================================
seg000:0000
seg000:0000 ; Segment type: Regular
seg000:0000 seg000 segment byte public '' use16
seg000:0000 assume cs:seg000
seg000:0000 assume es:nothing, ss:nothing, ds:nothing, fs:nothing, gs:nothing
seg000:0000 xor ax, ax
seg000:0002 mov ds, ax
seg000:0004 mov es, ax
seg000:0006 mov ss, ax
seg000:0008 mov sp, 7C00h
seg000:000B mov di, 0FC00h
seg000:000E stosd
seg000:0010 mov ax, 0B800h
seg000:0013 mov es, ax
seg000:0015 assume es:nothing
seg000:0015 mov ax, 3
seg000:0018 int 10h ; - VIDEO - SET VIDEO MODE
seg000:0018 ; AL = mode
seg000:001A inc ah
seg000:001C mov cx, 2000h
seg000:001F int 10h ; - VIDEO - SET CURSOR CHARACTERISTICS
seg000:001F ; CH bits 0-4 = start line for cursor in character cell
seg000:001F ; bits 5-6 = blink attribute
seg000:001F ; CL bits 0-4 = end line for cursor in character cell
seg000:0021 mov al, 0B6h ; '¦'
seg000:0023 out 43h, al ; Timer 8253-5 (AT: 8254.2).
seg000:0025 mov word ptr ds:0FC04h, 7D0Dh
seg000:002B mov si, 7D26h
seg000:002E xor edi, edi
seg000:0031 jmp short loc_AF
seg000:0033 ; ---------------------------------------------------------------------------
seg000:0033
seg000:0033 loc_33: ; CODE XREF: seg000:00D1j
seg000:0033 movzx edi, al
seg000:0037 and al, 0Fh
seg000:0039 and di, 0F0h
seg000:003D shl al, 1
seg000:003F shr di, 3 ; DATA XREF: seg000:0018r
seg000:003F ; seg000:001Fr
seg000:0042 push edi
seg000:0044 movzx bp, al
seg000:0047 mov bx, [bp+7D16h]
seg000:004B mov al, bl
seg000:004D out 42h, al ; Timer 8253-5 (AT: 8254.2).
seg000:004F mov al, bh
seg000:0051 out 42h, al ; Timer 8253-5 (AT: 8254.2).
seg000:0053 in al, 61h ; PC/XT PPI port B bits:
seg000:0053 ; 0: Tmr 2 gate =T= OR 03H=spkr ON
seg000:0053 ; 1: Tmr 2 data =- AND 0fcH=spkr OFF
seg000:0053 ; 3: 1=read high switches
seg000:0053 ; 4: 0=enable RAM parity checking
seg000:0053 ; 5: 0=enable I/O channel check
seg000:0053 ; 6: 0=hold keyboard clock low
seg000:0053 ; 7: 0=enable kbrd
seg000:0055 or al, 3
seg000:0057 out 61h, al ; PC/XT PPI port B bits:
seg000:0057 ; 0: Tmr 2 gate =T= OR 03H=spkr ON
seg000:0057 ; 1: Tmr 2 data =- AND 0fcH=spkr OFF
seg000:0057 ; 3: 1=read high switches
seg000:0057 ; 4: 0=enable RAM parity checking
seg000:0057 ; 5: 0=enable I/O channel check
seg000:0057 ; 6: 0=hold keyboard clock low
seg000:0057 ; 7: 0=enable kbrd
seg000:0059 xor di, di
seg000:005B mov cx, 7D0h
seg000:005E mov ax, 0F20h
seg000:0061 rep stosw
seg000:0063 mov ax, bp
seg000:0065 mov bl, 0Ah
seg000:0067 mul bl ; DATA XREF: seg000:00B2r
seg000:0069 mov di, ax
seg000:006B mov ax, bp
seg000:006D shl ax, 0Bh
seg000:0070 add ah, 20h ; ' '
seg000:0073 mov al, 20h ; ' '
seg000:0075 mov cx, 19h
seg000:0078
seg000:0078 loc_78: ; CODE XREF: seg000:0083j
seg000:0078 pusha
seg000:0079 mov cx, 0Ah
seg000:007C rep stosw
seg000:007E popa
seg000:007F add di, 0A0h ; 'à'
seg000:0083 loop loc_78
seg000:0085 pusha
seg000:0086 mov si, 7CF6h
seg000:0089 mov di, 7BAh
seg000:008C call sub_E8
seg000:008F mov si, ds:0FC04h
seg000:0093 mov di, 95Ah
seg000:0096 lodsb
seg000:0097 xor ah, ah
seg000:0099 add di, ax
seg000:009B push si
seg000:009C mov si, 7D09h
seg000:009F call sub_E8
seg000:00A2 pop si
seg000:00A3 call sub_E8
seg000:00A6 mov si, 7D09h
seg000:00A9 call sub_E8
seg000:00AC popa
seg000:00AD pop edi
seg000:00AF
seg000:00AF loc_AF: ; CODE XREF: seg000:0031j
seg000:00AF ; seg000:00C7j
seg000:00AF xor eax, eax
seg000:00B2 int 1Ah ; CLOCK - GET TIME OF DAY
seg000:00B2 ; Return: CX:DX = clock count
seg000:00B2 ; AL = 00h if clock was read or written (via AH=0,1) since the previous
seg000:00B2 ; midnight
seg000:00B2 ; Otherwise, AL > 0
seg000:00B4 mov ax, cx
seg000:00B6 shl eax, 10h
seg000:00BA mov ax, dx
seg000:00BC mov ebx, eax
seg000:00BF sub eax, ds:0FC00h
seg000:00C4 cmp eax, edi
seg000:00C7 jl short loc_AF
seg000:00C9 mov ds:0FC00h, ebx
seg000:00CE
seg000:00CE loc_CE: ; CODE XREF: seg000:00E1j
seg000:00CE ; seg000:00E6j
seg000:00CE lodsb
seg000:00CF or al, al
seg000:00D1 jnz loc_33
seg000:00D5 mov ds:0FC04h, si
seg000:00D9 lodsb
seg000:00DA or al, al
seg000:00DC jz short loc_E3
seg000:00DE call sub_E8
seg000:00E1 jmp short loc_CE
seg000:00E3 ; ---------------------------------------------------------------------------
seg000:00E3
seg000:00E3 loc_E3: ; CODE XREF: seg000:00DCj
seg000:00E3 mov si, 7D35h
seg000:00E6 jmp short loc_CE
seg000:00E8
seg000:00E8 ; --------------- S U B R O U T I N E ---------------------------------------
seg000:00E8
seg000:00E8
seg000:00E8 sub_E8 proc near ; CODE XREF: seg000:008Cp
seg000:00E8 ; seg000:009Fp ...
seg000:00E8 lodsb
seg000:00E9 or al, al
seg000:00EB jz short locret_F5
seg000:00ED stosb
seg000:00EE or byte ptr es:[di], 0Fh
seg000:00F2 inc di
seg000:00F3 jmp short sub_E8
seg000:00F5 ; ---------------------------------------------------------------------------
seg000:00F5
seg000:00F5 locret_F5: ; CODE XREF: sub_E8+3j
seg000:00F5 retn
seg000:00F5 sub_E8 endp
seg000:00F5
seg000:00F5 ; ---------------------------------------------------------------------------
seg000:00F6 aYouGotRickroll db 'You Got Rickroll',27h,'d',0
seg000:0109 dd 200E20h
seg000:010D aDIntro db 'D(Intro)',0
seg000:0116 db 0E3h ; ó
seg000:0117 db 0Bh
seg000:0118 db 97h ; ×
seg000:0119 db 0Ah
seg000:011A db 6Fh ; o
seg000:011B db 9
seg000:011C db 0E9h ; ù
seg000:011D db 8
seg000:011E db 0F0h ; ¨
seg000:011F db 7
seg000:0120 db 12h
seg000:0121 db 7
seg000:0122 db 0ADh ; í
seg000:0123 db 6
seg000:0124 db 0F1h ; ¸
seg000:0125 db 5
seg000:0126 db 83h ; Ã
seg000:0127 db 84h ; Ä
seg000:0128 db 60h ; `
seg000:0129 db 84h ; Ä
seg000:012A db 85h ; Å
seg000:012B db 17h
seg000:012C db 16h
seg000:012D db 15h
seg000:012E db 14h
seg000:012F db 83h ; Ã
seg000:0130 db 84h ; Ä
seg000:0131 db 60h ; `
seg000:0132 db 35h ; 5
seg000:0133 db 37h ; 7
seg000:0134 db 85h ; Å
seg000:0135 db 0
seg000:0136 db 32h ; 2
seg000:0137 aWeReNoStranger db 'We',27h,'re no strangers to love',0
seg000:0152 db 31h ; 1
seg000:0153 db 32h ; 2
seg000:0154 db 33h ; 3
seg000:0155 db 33h ; 3
seg000:0156 db 34h ; 4
seg000:0157 db 62h ; b
seg000:0158 db 61h ; a
seg000:0159 db 0F0h ; ¨
seg000:015A db 0
seg000:015B ; a___Verse_
seg000:015B a___Verse___ db '>...(Verse)...',0
seg000:016A db 31h ; 1
seg000:016B db 31h ; 1
seg000:016C db 32h ; 2
seg000:016D db 93h ; Ó
seg000:016E db 30h ; 0
seg000:016F db 67h ; g
seg000:0170 db 37h ; 7
seg000:0171 db 0F4h ; ¯
seg000:0172 db 31h ; 1
seg000:0173 db 31h ; 1
seg000:0174 db 32h ; 2
seg000:0175 db 33h ; 3
seg000:0176 db 31h ; 1
seg000:0177 db 33h ; 3
seg000:0178 db 64h ; d
seg000:0179 db 32h ; 2
seg000:017A db 31h ; 1
seg000:017B db 0F0h ; ¨
seg000:017C db 31h ; 1
seg000:017D db 31h ; 1
seg000:017E db 32h ; 2
seg000:017F db 33h ; 3
seg000:0180 db 31h ; 1
seg000:0181 db 60h ; `
seg000:0182 db 34h ; 4
seg000:0183 db 34h ; 4
seg000:0184 db 34h ; 4
seg000:0185 db 35h ; 5
seg000:0186 db 0F4h ; ¯
seg000:0187 db 0E3h ; ó
seg000:0188 db 34h ; 4
seg000:0189 db 35h ; 5
seg000:018A db 33h ; 3
seg000:018B db 34h ; 4
seg000:018C db 34h ; 4
seg000:018D db 34h ; 4
seg000:018E db 35h ; 5
seg000:018F db 64h ; d
seg000:0190 db 0F0h ; ¨
seg000:0191 db 31h ; 1
seg000:0192 db 32h ; 2
seg000:0193 db 33h ; 3
seg000:0194 db 61h ; a
seg000:0195 db 34h ; 4
seg000:0196 db 35h ; 5
seg000:0197 db 94h ; Ô
seg000:0198 db 0
seg000:0199 db 34h ; 4
seg000:019A aNeverGonnaGive db 'Never gonna give you up',0
seg000:01B2 db 10h
seg000:01B3 db 11h
seg000:01B4 db 13h
seg000:01B5 db 11h
seg000:01B6 db 45h ; E
seg000:01B7 db 45h ; E
seg000:01B8 db 94h ; Ô
seg000:01B9 db 0
seg000:01BA ; a___Chorus_
seg000:01BA a___Chorus___ db '>...(Chorus)...',0
seg000:01CA db 10h
seg000:01CB db 11h
seg000:01CC db 13h
seg000:01CD db 11h
seg000:01CE db 44h ; D
seg000:01CF db 44h ; D
seg000:01D0 db 93h ; Ó
seg000:01D1 db 10h
seg000:01D2 db 11h
seg000:01D3 db 13h
seg000:01D4 db 11h
seg000:01D5 db 63h ; c
seg000:01D6 db 34h ; 4
seg000:01D7 db 62h ; b
seg000:01D8 db 60h ; `
seg000:01D9 db 30h ; 0
seg000:01DA db 64h ; d
seg000:01DB db 0C3h ; +
seg000:01DC db 10h
seg000:01DD db 11h
seg000:01DE db 13h
seg000:01DF db 11h
seg000:01E0 db 65h ; e
seg000:01E1 db 35h ; 5
seg000:01E2 db 94h ; Ô
seg000:01E3 db 10h
seg000:01E4 db 11h
seg000:01E5 db 13h
seg000:01E6 db 11h
seg000:01E7 db 67h ; g
seg000:01E8 db 32h ; 2
seg000:01E9 db 93h ; Ó
seg000:01EA db 10h
seg000:01EB db 11h
seg000:01EC db 13h
seg000:01ED db 11h
seg000:01EE db 63h ; c
seg000:01EF db 34h ; 4
seg000:01F0 db 0C2h ; T
seg000:01F1 db 31h ; 1
seg000:01F2 db 30h ; 0
seg000:01F3 db 64h ; d
seg000:01F4 db 0F3h ; º
seg000:01F5 db 0
seg000:01F6 db 0
seg000:01F7 db 0
seg000:01F8 db 0
seg000:01F9 db 0
seg000:01FA db 0
seg000:01FB db 0
seg000:01FC db 0
seg000:01FD db 0
seg000:01FE dw 0AA55h
seg000:01FE seg000 ends
seg000:01FE
seg000:01FE
seg000:01FE end

Coty · **Joined:** Thu Feb 12, 2009 5:12 pm **Posts:** 286

hmm... something tells me I need to get a new disassembler... here is what I got on the first 20 lines when I disassembled it:

Code:

skeq v1,C0
???
mov v14,v12
jmi C00
add v12,BF
scdown 14
mov v6,AB
jmi 88E
rand v0,0B8
scdown 0
rand v13,D10
???
jmi 900
jsr 0CD
jmp 0B0
jmi 6E6
skne v3,C7
scdown 4
add v14,D

Messed up huh?

@Zenith: thanks, now my collection is complete

Zenith · **Joined:** Tue Apr 10, 2007 4:42 pm **Posts:** 224

Masterkiller wrote:

It seems the code is 0xF5 (245) bytes. The rest are strings and probably the melody itself

Quite impressive!
P.S. He sets ES to 0, not using it as 0, then sets it to 0xB800 for video memory. Suppressing MOV ES, ax where ax=0 will free 2 more bytes

Well actually, setting ES to 0 allows me to use stosd instead of something like mov dword [0x00:0xFC00], 0. :wink:

(Oh well, I'll check which method takes up less space sometime).

And in case you missed it, I posted the code for my demo right before you posted your disassembly

.

@Coddy: Whoa! I think you've got a disassembler for a completely different architecture there. (Did some research and it seems to be output for CHIP-8 VM opcodes - back in the good old days... See here and here.)

Coty · **Joined:** Thu Feb 12, 2009 5:12 pm **Posts:** 286

sweet, its pong time

beep........beep....beep.beep......beep.....beeeep woo! I lost

I thought that site looked old

Troy Martin · **Posted:** Mon Jun 01, 2009 8:17 pm

Coddy wrote:

hmm... something tells me I need to get a new disassembler... here is what I got on the first 20 lines when I disassembled it:

Code:

<snip>

Messed up huh?

@Zenith: thanks, now my collection is complete

... that's not an x86 disassembler... what the hell program is that?

EDIT: thanks Zenith.

Dex · **Joined:** Fri Jan 27, 2006 12:00 am **Posts:** 1444

Nice code Zenith, you had my vote.
Coddy you can add this "AI pong" to your collection, its only 265 byte.

Code:

; small AI game demo, compile with fasm.
; Original written by Luks, for nasm.
; c:\fasm game.asm game.com
org 0x100
use16
START:

mov     al,0x13
int     0x10

MAIN:
push    word 0x8000
pop     es
push    cs
pop     ds

mov     cx,0xFFFF
mov     al,0
rep     stosb
mov     si,BALLYI
call    PutLine
mov     bx,[si-6]
mov     dx,[si-4]
cmp     dx,195
jb      CMPY
jmp     NEGY
CMPY:
cmp     dx,1
jg      ADDY
NEGY:
neg     word[si]
ADDY:
add     dx,[si]
dec     si
dec     si
cmp     bx,310
jb      CMPX
jmp     NEGX
CMPX:
cmp     bx,6
jg      ADDX
NEGX:
neg     word[si]
ADDX:
add     bx,[si]
sub     si,8
mov     di,dx
imul    di,320
add     di,bx
mov     cl,4
BALL:
mov     [es:di], dword 0x0f0f0f0f
add     di,320
loop    BALL
mov     [si+4],bx
mov     [si+6],dx

; PADS
mov     bp,si
cmp     [si+9],byte 0
je      PAD2
PAD1:
call    PADCHK
jmp     PADS
PAD2:
add     bp,2
call    PADCHK

PADS:
mov     ax,[si]
mov     di,2
call    DRAWPAD
mov     ax,[si+2]
mov     di,314
call    DRAWPAD
push    es
pop     ds
push    word 0xA000
pop     es
mov     cx,32000
xor     si,si
mov     di,si
rep     movsw
mov     ah,0x11
int     0x16
jz      MAIN
mov     ax,0x0003
int     0x10

DRAWPAD:
imul    ax,320
add     di,ax
mov     cx,16
PAD:
mov     [es:di], dword 0x0f0f0f0f
add     di,320
loop    PAD
ret

PADCHK:
cmp     dx,[bp]
jge     PADDOWN
dec     word [bp]
jmp     ENDCHK
PADDOWN:
sub     dx,12
cmp     dx,[bp]
jbe     ENDCHK
inc     word [bp]
ENDCHK:
ret

PutLine:
mov     al,15
mov     di,158
mov     cl,198
@@:
add     di,319
stosb
loop    @b
xor     di,di
call    Hline
xor     dx,dx
xor     di,di
mov     cl,199
Gridlp3:
stosb
add     di,318
stosb
loop    Gridlp3
call    Hline
ret
               
Hline:
mov     al,15
mov     cx,320
rep     stosb
ret

PAD1Y   dw      100
PAD2Y   dw      100
BALLX   dw      160
BALLY   dw      100
BALLXI  dw      -1
BALLYI  dw      -1

I did not write it, i just converted it.

Coty · **Joined:** Thu Feb 12, 2009 5:12 pm **Posts:** 286

that cool, hmm... It gives me an inspiration for...... bootible pong

a427 · **Joined:** Sun Mar 15, 2009 9:45 pm **Posts:** 40

Any chances to see a fourth 512-byte asm compo organized ? :roll:

(I managed to successfully miss the first three editions, and hence still have got a potential entry ready and waiting.. grumble..)

earlz · **Joined:** Thu Jul 07, 2005 11:00 pm **Posts:** 1546

What? I missed it again?

Troy Martin · **Posted:** Mon Jun 29, 2009 9:46 am

We're still "discussing" the next one in some other thread somewhere. Not sure when it will pop into existence though.

EDIT: spelling fail.

Coty · **Joined:** Thu Feb 12, 2009 5:12 pm **Posts:** 286

I can't wait, maybe I can finely get a fourth folder on my site directory

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The Third 512-byte OS Contest!

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