INT 21 U - OS/2 v2.1+ Virtual DOS MachineA special type of virtual machine provided by OS/2 version 2.0, in which a copy of MS-DOS or an MS-DOS compatible operating system (or even an incompatible 8086 operating system) is run and appears to have full control of the system. See also Virtual Machine, INT 21h Function 64h. - OS/2 API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running. Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. DosQFSAttach AH = 64h BX = 00B6h (API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running. Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. ordinal) CX = 636Ch (magic value "cl") DS = user's data segment ES:DI -> FSQAttachStruc (see #01749) Return: CF set on error AX = error code (see #01680 at AH=59h/BX=0000h) CF clear if successful AX = 0000h data buffer filled SeeAlso: AH=64h/CX=636Ch Format of OS/2 Virtual DOS MachineA special type of virtual machine provided by OS/2 version 2.0, in which a copy of MS-DOS or an MS-DOS compatible operating system (or even an incompatible 8086 operating system) is run and appears to have full control of the system. See also Virtual Machine, INT 21h Function 64h. FSQAttachStruc: Offset Size Description (Table 01749) 00h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. reserved 04h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. pointer to the offset of the data buffer length 08h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. pointer to the offset of the data buffer 0Ch WORD FSA Info level 0Eh WORD ordinal index into table 10h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. pointer to the offset of the device name Notes: The segment value of the buffer, buffer length, and device name MUST all be the same. It is defined on entry in the DS register. The details of each info level are defined in the OS/2 CP Reference.