INT 2F C - MS Windows - "DOSMGR" VIRTUAL DEVICE 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. AX = 1607h BX = 0015h (VxDA virtual device driver for Windows 3.x or 95. So called because nearly all of the Windows 3.0 drivers had names of the form "VdeviceD". See also device driver. identifier of "DOSMGR") CX = function 0000h query instance processing DX = 0000h Return: CX = state 0000h not instanced other instanced (DOS 5+ kernel returns 0001h) DX = segment of DOS drivers or 0000h for default of 0070h ES:BX -> patch table (see #02637) 0001h set patches in DOS DX = bit mask of patch requests (see #02636) Return: AX = B97Ch BX = bit mask of patches applied (see #02636) DX = A2ABh 0002h remove patches in DOS (ignored by DOS 5.0 kernel) DX = bit mask of patch requests (see #02636) Return: CX = 0000h (DOS 5-6) Note: return values are ignored by DOSMGR in Windows 3.1 0003h get size of DOS data structures DX = bit mask of request (only one bit can be set) bit 0: Current Directory StructureThe data record used by DOS to keep track of the current directory on a drive; whether the drive is valid, network, SUBSTituted, or JOINed; and other pertinent information. See also INT 21h Function 52h. size Return: if supported request: AX = B97Ch CX = size in bytes of requested structure DX = A2ABh else: CX = 0000h all other registers preserved 0004h determine instanced data structures Return: AX = B97Ch if supported DX = A2ABh if supported (DOS 5+ kernel returns 0000h) BX = bit mask of instanced items bit 0: CDSsee Current Directory Structure bit 1: SFTsee System File Table bit 2: device list bit 3: DOS swappable data area 0005h get device driver size ES = segment of device driver Return: DX:AX = 0000h:0000h on error (not dev. driver segment) DX:AX = A2ABh:B97Ch if successful BX:CX = size of device driver in bytes Notes: DOSMGR (DOS Manager) will check whether the OEM(Original Equipment Manufacturer) a company which purchases components that are resold as part of its own products under the company's own brand name, e.g. a Gateway 2000-branded monitor may actually be a Mag or NEC monitor. DOS/BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. data has been instanced via this 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. and will not perform its own default instancing of the normal DOS/BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. data if so; if this 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. is not supported, DOSMGR will also try to access instancing data through INT 2F/AX=1603h these functions are supported by the DOS 5+ kernel; DOSMGR contains tables of instancing information for earlier versions of DOS see Geoff Chappell's book DOS Internals for additional discussions of DOSMGR's behavior and instancing in general SeeAlso: AX=1603h,AX=1605h,AX=1607h/BX=000Ch,AX=1607h/BX=0014h SeeAlso: AX=1684h"DEVICE 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." Bitfields for DOSMGR patch requests: Bit(s) Description (Table 02636) 0 enable critical sections 1 NOP setting/checking user ID 2 turn INT 21/AH=3Fh on STDIN into polling loop 3 trap stack fault in "SYSINIT" to WIN386 4 BIOS(Basic Input/Output System) A set of standardized calls giving low-level access to the hardware. The BIOS is the lowest software layer above the actual hardware and serves to insulate programs (and operating systems) which use it from the details of accessing the hardware directly. patch to trap "Insert disk X:" to WIN386 Format of DOSMGR patch table: Offset Size Description (Table 02637) 00h 2 BYTEs DOS version (major, minor) 02h WORD offset in DOS data segment of "SAVEDS" 04h WORD offset in DOS data segment of "SAVEBX" 06h WORD offset in DOS data segment of InDOS flag 08h WORD offset in DOS data segment of User ID word 0Ah WORD offset in DOS data segment of "CritPatch" table to enable critical section calls (see INT 2A/AH=80h) 0Ch WORD (DOS 5+ only) offset in DOS data segment of "UMB_HEAD", containing segment of last MCBsee Memory Control Block in conventional memory