China DOS Union

Originally posted by s11ss at 2008-12-9 22:48:


By no keypress, do you mean directly pressing Enter? If only function 0 is used, then al is 0d

No keypress means not touching the keyboard at all.

Really powerful. People like me who don't understand assembly can only sigh in admiration.

In the program above, mov ax,0 is 3 bytes long. Changing it to mov ah,0 or xor ah,ah or sub ah,ah saves 1 byte.

Actually, the shortest program of this kind only needs 8 bytes.

DEBUG
a
mov ah,0
int 16h
mov ah,4Ch
int 21h

rcx
8
nkeycode.com
w
q

<!Originally posted by 本是 at 2008-12-10 02:31 PM:
In the program above, mov ax,0 is 3 bytes long. Changing it to mov ah,0 or xor ah,ah or sub ah,ah saves 1 byte.

Actually, the shortest program of this kind only needs 8 bytes.

DEBUG
a
mov ah,0
int 16h
mov ah,4Ch
...

What I mean is not using function 1 of int 16h, and it seems it still works~

Actually it seems you don't need to write a com either, you can call it directly with debug :)]>

Originally posted by 本是 at 2008-12-10 14:31:
In the program above, mov ax,0 is 3 bytes long. Changing it to mov ah,0 or xor ah,ah or sub ah,ah saves 1 byte.

Actually, the shortest program of this kind only needs 8 bytes.

DEBUG
a
mov ah,0
int 16h
mov ah,4Ch
...

Still a misunderstanding. Try the example on the 12th floor and you'll find where it differs from the program above

@echo off

call inc 2>nul

if %errorlevel%==1 (

   >inc.src echo ecs:100 B8 00 01 CD 16 B8 00 00 74 02 CD 16 B4 4C CD 21

   >>inc.src echo rcx

   >>inc.src echo 10

   >>inc.src echo w

   >>inc.src echo q

   debug inc.com < inc.src 2>nul 1>nul

   del inc.src

)

:loop

inc





echo %errorlevel%







if not %errorlevel%==0 (

   if %errorlevel%==81 goto :eof ::q or Q exit

   if %errorlevel%==113 goto :eof

) 

ping -n 2 127.1>nul

goto loop

Or try this one. When there is no input, the loop keeps running. It doesn't wait for input.

This thread is mainly about using int 16h with ah=1, (that is also its main difference from choice). If that isn't explained clearly, then it has no meaning at all.
Maybe my ability to express it isn't good enough. There are lots of experts here in the forum—can someone help me explain it clearly?

[ Last edited by wangff on 2008-12-10 at 17:51 ]

Originally posted by s11ss at 2008-12-10 14:55:


What I mean is not using function 1 of int 16h, and it seems it still works~

Actually it seems you don't need to write a com either, you can call it directly with debug :)

Not using a com works too, but you need a script, such as c.txt

a

MOV     AX,0100

INT     16

MOV     AX,0000

JZ      010C

INT     16

MOV     AH,4C

INT     21



g

q

p code:

@echo off



:loop

debug <c.txt>nul





echo %errorlevel%







if not %errorlevel%==0 (

   if %errorlevel%==81 goto :eof ::q or Q exit

   if %errorlevel%==113 goto :eof

) 

ping -n 2 127.1>nul

goto loop

Same effect.

[ Last edited by wangff on 2008-12-10 at 17:52 ]

Example using only int 16h function ah=0:

script: a.txt

a

  mov ah,0

  int 16

  mov ah,4C

  int 21



g

q

p code:

@echo off



:loop

debug <a.txt>nul





echo %errorlevel%







if not %errorlevel%==0 (

   if %errorlevel%==81 goto :eof ::q or Q exit

   if %errorlevel%==113 goto :eof

) 

ping -n 2 127.1>nul

goto loop

You can do it without a temporary file

goto :main

a

;MOV     AX,0100

;INT     16

MOV     AX,0000

;JZ      010C

INT     16

MOV     AH,4C

INT     21



g

q



:main

@echo off



:loop

debug <"%~f0">nul





echo %errorlevel%







if not %errorlevel%==0 (

   if %errorlevel%==81 goto :eof ::q or Q exit

   if %errorlevel%==113 goto :eof

) 

ping -n 2 127.1>nul

goto loop

Add two lines to quickly clear the display of “goto :main” and support Chinese display (tested on XP)

......

:main
cls
@echo off
chcp 437|graftabl 936>nul

......

Good post

Improved parameter-capable version of the 2nd floor:

@echo off

goto main

a

MOV     AL,

CMP     AL,20

JNZ     0110

MOV     AH,01

INT     16

MOV     AX,0000

JZ      0112

INT     16

MOV     AH,4C

INT     21



g

q

:main

chcp 437|graftabl 936>nul

set/p =input:<nul

::with a parameter (any parameter), wait for one character of input and return it through errorlevel

debug a.com i<"%~f0">nul 2>nul

echo %errorlevel%

:loop

::without parameters, detect whether there is a keypress; none:errorlevel=0, if yes then errorlevel=key value, can be used to dynamically detect keypresses while running

debug<"%~f0">nul

echo %errorlevel%

if not %errorlevel%==0 (

   if %errorlevel%==81 goto :eof ::q or Q exit

   if %errorlevel%==113 goto :eof

) 

ping -n 2 127.1>nul

goto loop

Run automatically:

@echo off

goto main

a

MOV     AL,

CMP     AL,20

JNZ     0110

MOV     AH,01

INT     16

MOV     AX,0000

JZ      0112

INT     16

MOV     AH,4C

INT     21



g

q

:main

chcp 437|graftabl 936>nul

set/p =Waiting...<nul&set/a n=0

:loop

set/a n+=1

set/p =.%n%<nul

debug<"%~f0">nul

if not %errorlevel%==0 (

   if %errorlevel%==81 goto :eof ::q or Q exit

   if %errorlevel%==113 goto :eof

) 

if %n% gtr 5 goto p1

ping -n 2 127.1>nul

goto loop



:p1

echo.

echo Time's up, run automatically!

pause

You guys really are amazingly creative!

Saying goodbye to choice sounds a bit far-fetched though, choice is still relatively powerful :)