Format of PC-IPC parameter block:
Offset	Size	Description	)
 00h	WORD	caller's ID
 02h	WORD	to ID
 04h	WORD	command code (see #03269)
 06h	WORD	returned status (see #03270)
 08h	WORD	returned error code (see #03271)
 0Ah	WORD	size of data
 0Ch	DWORD	pointer to data buffer