Notification Function 0007h Switcher Exit

mov bx, Flags ;indicates whether other task switchers present

les di, Service ;es:di is address of service-function handler

mov ax, 0007h ;Switcher Exit

call [Notification] ;client program's notification-function handler

Switcher Exit (Notification Function 0007h) notifies global client programs that the task switcher is no longer active.

Parameters

Flags

Specifies whether other task switchers are present in the system. If bit 0 is 1, the calling task switcher is the only switcher present. If bit 0 is zero, at least one other task switcher remains after the calling task switcher exits. All other bits are reserved and must be zero.

Service

Points to the service-function handler for the task switcher. If this address is NULL, the call-in function handler is no longer present and cannot be called.

Return Value

The AX register contains 0000h.

Comments

A task switcher calls this function. Global programs that receive this call should disable any extra processing they were running in order to coexist with the task switcher.

This function can be called by programs that control the task switcher, rather than by the task switcher itself. For this reason, the service-function-handler address specified in the ES:DI registers may differ from addresses passed with other notification functions and may be NULL.

The task switcher enables interrupts before calling the client program. The client program can call any MS-DOS system function. Although the client program modifies the AX register, it must preserve all other registers.