INT 2F - DOS 5+ TASK SWITCHER - INSTALLATION CHECK AX = 4B02h BX = 0000h ES:DI = 0000h:0000h Return: ES:DI = 0000h:0000h if task switcher not loaded ES:DI -> task switcher entry point (see #02819) if loaded AX = 0000h Notes: the returned entry point is that for the most-recently loaded task switcher; the entry points for prior task switchers may be determined with the "get version" call (see #02819) this function is supported by PCIBM PC Tools v8+ CPTASK SeeAlso: AX=4A05h,AX=4B03h (Table 02819) Call task switcher entry point with: AX = 0000h get version Return: CF clear if successful AX = 0000h ES:BX -> task switcher version struct (see #02820) CF set if unsupported function AX = 0001h test memory region ES:DI -> first byte to be tested CX = size of region to test Return: CF clear if successful AX = memory type of tested region 0000h global 0001h global and local 0002h local (replaced on session switch) CF set if unsupported function AX = 0002h suspend switcher ES:DI -> new task switcher's entry point Return: CF clear if successful AX = state 0000h switcher has been suspended 0001h switcher not suspended, new switcher must abort 0002h switcher not suspended, but new switcher may run anyway CF set if unsupported function AX = 0003h resume switcher ES:DI -> new task switcher's entry point Return: CF clear if successful AX = 0000h CF set if unsupported function AX = 0004h hook notification chain ES:DI -> callback info structure to be added to chain (see #02817) Return: CF clear if successful AX = 0000h CF set if unsupported function AX = 0005h unhook notification chain ES:DI -> callback info structure to be removed from chain (see #02817) Return: CF clear if successful AX = 0000h CF set if unsupported function AX = 0006h query 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. support BX = asynchronous 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. identifier Return: CF clear if successful AX = 0000h ES:BX -> 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. info structure (see #02821) for the client which provides the highest level of 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. support CF set if unsupported function Format of task switcher version structure: Offset Size Description (Table 02820) 00h WORD major version of supported protocol (current protocol is 1.0) 02h WORD minor version of supported protocol 04h WORD major version of task switcher 06h WORD minor version of task switcher 08h WORD task switcher ID (see AX=4B03h) 0Ah WORD operation flags bit 0: set if task switcher disabled bits 1-15: reserved (0) 0Ch DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. pointer to ASCIZA NUL-terminated ASCII string. The ASCIZ string "ABC" consists of the four bytes 41h, 42h, 43h, and 00h. Unless otherwise specified, maximum lengths given in the interrupt list do not include the terminating NUL. task switcher name ("MS-DOS Shell Task Switcher" for DOSSHELL task switcher) 10h DWORDDoubleword; four bytes. Commonly used to hold a 32-bit segment:offset or selector:offset address. pointer to previous task switcher's entry point or 0000h:0000h Format of 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. info structure: Offset Size Description (Table 02821) 00h WORD size of structure in bytes (000Ah) 02h WORD 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. identifier 0001h NetBIOSOne of a number of low-level device-independent network interfaces; the other major interfaces are Novell's IPX and the Internet's IP (Internet Protocol, the lower-level portion of TCP/IP). 0002h 802.2 0003h TCP/IPThe protocol suite originally developed by DARPA for use on its ARPAnet network, which is now known as the Internet. See also IP, TCP. 0004h LAN Manager named pipes 0005h Novell NetWare IPX(Internetwork Packet Exchange) A low-level layer of Novell's NetWare networking software. 04h WORD major version \ of highest version of 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. for which the support 06h WORD minor version / level specified in the next field is provided 08h WORD support level 0001h minimal support 0002h API-level support 0003h switcher compatibility 0004h seamless compatibility