Int 15 Fn 01  - Amstrad PC1512 - Write Data To Non-volatile RAM            [b]

   AH = 01h
   AL = NVRAM location (00h to 3Fh)
   BL = NVRAM data value

Return: AH = return code
       00h OK
       01h address bad
       02h write error

See Also: AH=02h"Amstrad"

Format of 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
       bit 7: set if date/time being updated
       bits 6-4: time base speed, default 010 = 32768 Hz
       bits 3-0: interrupt rate selection, default 0110 = 1024 Hz
 0Bh   BYTE    RTC status register B (see below)
 0Ch   BYTE    RTC status register C (read-only)
       bit 7: IRQF flag
       bit 6: PF flag
       bit 5: AF flag
       bit 4: UF flag
 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

Bitfields for RTC status register B:
 bit 7 clear if normal update, set if abort update
 bit 6 periodic interrupt enable
 bit 5 alarm interrupt enable
 bit 4 update end interrupt enable
 bit 3 square wave enable
 bit 2 date mode (clear = BCD, set = binary)
 bit 1 24-hour format
 bit 0 daylight saving time enable