Category: DOS-based task switchers/multitaskers
Flags: callout or callback (usually hooked rather than called)
INT 2F - DOS 5+ TASK SWITCHER - BUILD CALLOUT CHAIN AX = 4B01h CX:DX -> task switcher entry point (see #02819) ES:BX = 0000h:0000h Return: ES:BX -> callback info structure (see #02817) or 0000h:0000h Notes: called by the task switcher this function is hooked by clients which require notification of task switcher activities; the call must first be passed on to the prior handler with registers unchanged using a simulated interrupt. On return, the client must build a callback info structure and store the returned ES:BX in the "next" field, then return the address of its own callback info structure. a client program must add itself to the notification chain if it provides services to other programs; before terminating, it must remove itself from the chain by calling the task switcher's entry point with AX=0005h (see #02819) the task switcher entry point should not be saved, as it is subject to change and will be provided on any notification call the Windows 3.1 Standard Mode supports this API SeeAlso: AX=160Bh,AX=4B02h