INT 16 - AT.COM version 8/26/87 - API
        AX = 8765h
        BX = 4321h
        CX = ??? or FFFFh
        if CX = FFFFh
                DX = number of event to remove or FFFFh
Return: ES:BX -> event record array
Note:   AT.COM is a resident scheduler by Bill Frolik

Format of event record:
Offset  Size    Description
 00h    BYTE    in-use flag (00h free, 01h in use, FFh end of array)
 01h    BYTE    day of date on which to trigger
 02h    BYTE    month of date on which to trigger
 03h    BYTE    trigger time, minute
 04h    BYTE    trigger time, hour
 05h    WORD    offset of command to be executed