Format of DUBLDISK data record:
Offset	Size	Description	)
 00h	WORD	(call) signature 4444h
 02h	BYTE	(call) function
			00h ???
			01h ???
---function 00h---
 02h	BYTE	(ret) ???
 03h	BYTE	(ret) ???
---function 01h---
 02h	WORD	(ret) 4444h
 04h	WORD	allocation unit size???
 06h	WORD	???
 08h	WORD	???
 0Ah	BYTE	???