Format of CDTSR internal variable structure:
Offset	Size	Description	)
 00h	BYTE	hotkey scan code (see #00006)
 01h	BYTE	hotkey shift states
 02h	BYTE	flag: repeat
 03h	BYTE	flag: custom repeat
 04h	BYTE	flag: background polling
 05h	DWORD	(read-only) internal timing variable
 09h	DWORD	current track play position, in frames
 0Dh	DWORD	current disk play position, in frames
 11h	BYTE	number of entries in track program
 12h	BYTE	index into track program currently playing (FFh if not playing)
 13h 100 BYTEs	track program (each byte contains one track number)
 77h	BYTE	saved cursor end scan line
 78h	BYTE	saved cursor start scan line
 79h	BYTE	currently playing track
 7Ah	BYTE	CD driver media-change flag
 7Bh	WORD	video base segment during last popup
 7Dh	WORD	video page offset during last popup
 7Fh	BYTE	currently-selected track
 80h	DWORD	begin of custom repeat, in frames
 84h	DWORD	end of custom repeat, in frames
 88h	WORD	track program index of top list item