Format of Amstrad NVRAM:
Offset	Size	Description	)
 00h	BYTE	time of day: seconds
 01h	BYTE	alarm time: seconds
 02h	BYTE	time of day: minutes
 03h	BYTE	alarm time: minutes
 04h	BYTE	time of day: hours
 05h	BYTE	alarm time: hours
 06h	BYTE	day of week, 1 = Sunday
 07h	BYTE	day of month
 08h	BYTE	month
 09h	BYTE	year mod 100
 0Ah	BYTE	RTC status register A (see #00406)
 0Bh	BYTE	RTC status register B (see #00407)
 0Ch	BYTE	RTC status register C (read-only) (see #00408)
 0Dh	BYTE	RTC status register D
		bit 7: battery good
 0Eh  6 BYTEs	time and date machine last used
 14h	BYTE	user RAM checksum
 15h	WORD	Enter key scancode/ASCII code
 17h	WORD	Forward delete key scancode/ASCII code
 19h	WORD	Joystick fire button 1 scancode/ASCII code
 1Bh	WORD	Joystick fire button 2 scancode/ASCII code
 1Dh	WORD	mouse button 1 scancode/ASCII code
 1Fh	WORD	mouse button 2 scancode/ASCII code
 21h	BYTE	mouse X scaling factor
 22h	BYTE	mouse Y scaling factor
 23h	BYTE	initial VDU mode and drive count
 24h	BYTE	initial VDU character attribute
 25h	BYTE	size of RAM disk in 2K blocks
 26h	BYTE	initial system UART setup byte
 27h	BYTE	initial external UART setup byte
 28h 24 BYTEs	available for user application
Note:	bytes 00h-0Dh are the same on the IBM AT as they are used/updated by
	  the clock chip