en:docs:dos:api:int21:50

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en:docs:dos:api:int21:50 [2021/05/02 05:12] – created prokusheven:docs:dos:api:int21:50 [2024/05/03 02:27] (current) – prokushev
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 ===== Notes ===== ===== Notes =====
  
- DOS uses the current PSP address to determine which processes own files +DOS uses the current PSP address to determine which processes own files and memory; it corresponds to process identifiers used by other OSs 
-   and memory; it corresponds to process identifiers used by other OSs + 
- under DOS 2.x, this function cannot be invoked inside an INT 28h +under DOS 2.x, this function cannot be invoked inside an INT 28h handler without setting the Critical Error flag 
-   handler without setting the Critical Error flag + 
- under MS-DOS 3.0+ and DR DOS 3.41+, this function does not use any of +under MS-DOS 3.0+ and DR DOS 3.41+, this function does not use any of the DOS-internal stacks and may thus be called at any time, even during another INT 21h call 
-   the DOS-internal stacks and may thus be called at any time, even + 
-   during another INT 21h call +some Microsoft applications such as Quick C 2.51 use segments of 0000h and FFFFh and direct access to the SDA (see #01687 at AX=5D06h) to test whether they are running under MS-DOS rather than a compatible OS; although one should only call this function with valid PSP addresses, any program hooking it should be prepared to handle invalid addresses 
- some Microsoft applications such as Quick C 2.51 use segments of 0000h + 
-   and FFFFh and direct access to the SDA (see #01687 at AX=5D06h) to +this function is supported by the OS/2 compatibility box 
-   test whether they are running under MS-DOS rather than a compatible + 
-   OS; although one should only call this function with valid PSP +this call was undocumented prior to the release of DOS 5.0
-   addresses, any program hooking it should be prepared to handle +
-   invalid addresses +
- this function is supported by the OS/2 compatibility box +
- this call was undocumented prior to the release of DOS 5.0+
                      
 ===== See also ===== ===== See also =====
  
- AH=26h,AH=51h,AH=62h+AH=[[en:docs:dos:api:int21:26|26h]],AH=[[en:docs:dos:api:int21:51|51h]],AH=[[en:docs:dos:api:int21:62|62h]]
  
 ===== Note ===== ===== Note =====