HELP: Int 21h stuff and/or doskey sorse 
Author Message
 HELP: Int 21h stuff and/or doskey sorse

Hello PPL !

Welp I have 2 problems ->
1st one: Can somebody post here prog which will hook 21h int but in such
         a way so it'll be activated twice -> before the original routine
         and after it .
2nd one: Can somebody post doskey sorse or something like doskey ? ( i.e.
         programm which works only in plain dos prompt.

C U :-)



Wed, 18 Jun 1902 08:00:00 GMT  
 HELP: Int 21h stuff and/or doskey sorse

Quote:

> Hello PPL !

> Welp I have 2 problems ->
> 1st one: Can somebody post here prog which will hook 21h int but in such
>          a way so it'll be activated twice -> before the original routine
>          and after it .
> 2nd one: Can somebody post doskey sorse or something like doskey ? ( i.e.
>          programm which works only in plain dos prompt.

> C U :-)

 Hi!

 About the first one :

  Before calling original ISR do POPF. Then iret from there will return
  control to your ISR. About the second one - sorry..., do not have it.
  But I'll check and if nobody will send it I'll try to fix it.

       Denny.



Wed, 18 Jun 1902 08:00:00 GMT  
 HELP: Int 21h stuff and/or doskey sorse

Quote:
> Hello PPL !

> Welp I have 2 problems ->
> 1st one: Can somebody post here prog which will hook 21h int but in such
>          a way so it'll be activated twice -> before the original routine
>          and after it .
> 2nd one: Can somebody post doskey sorse or something like doskey ? ( i.e.
>          programm which works only in plain dos prompt.

> C U :-)

1) I'm assuming you are doing this with assembly (since anything else
would be silly).  Save all of the registers, run your ISR, restore all of
the registers, do a PUSHF and do a long CALL to original DOS.  Then after
it gets back, do a PUSHF immediately, save the other registers, run your
ISR (2nd half), then restore all registers (including flags) and do a
RETF 2 (this is equivalent to an IRET but it throws away the flags).

2)  Look for CED.  It's an old DOS add-on with a few hints on how it
worked.  I haven't seen it around much (and I don't have a copy), but it
was great in its time.



Wed, 18 Jun 1902 08:00:00 GMT  
 
 [ 3 post ] 

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