Format of Hewlett-Packard ROM ID at F000h:00F8h:
Offset	Size	Description	)
 00h  2 BYTEs	signature "HP" (48h 50h)
 02h  2 BYTEs	00h 00h
 04h	BYTE	secondary code revision
 05h	BYTE	primary code revision
 06h	BYTE	date code, year-1960 (BCD)
 07h	BYTE	date code, week of year (BCD)
SeeAlso: #00517,#00519