Softcard III: Accessing Apple III system clock under CP/M

Softcard III: Accessing Apple III system clock under CP/M

The Apple III clock is accessible from machine language under CP/M.  There
are two call addresses in BIOS used to read and set the clock.  Both use a
common 18 byte area for returning the Date/Time or for setting the clock.
If no clock is installed, the byte at 0DFE0H is 00H.
 
        To Set Clock:       Call  0DF89H
 
        To Read Clock:      Call  0DF86H
 
Example:  Friday, March 21, 1982, 1:27 PM and 41.234 seconds is represented
as the ASCII string:  "198203216132741234".
 
                     Addresses             Contents
                                          Hex  ASCII
   Year:              0DFE0H               31   (1)
                      0DFE1H               39   (9)
                      0DFE2H               38   (8)
                      0DFE3H               32   (2)
   Month:             0DFE4H               30   (0)
                      0DFE5H               33   (3)
   Day:               0DFE6H               32   (2)
                      0DFE7H               31   (1)
   Day of week:       0DFE8H               36   (6) (1=Sunday)
   Hour:              0DFE9H               31   (1)
                      0DFEAH               33   (3)
   Minute:            0DFEBH               32   (2)
                      0DFECH               37   (7)
   Second:            0DFEDH               34   (4)
                      0DFEEH               31   (1)
   Tenths:            0DFEFH               32   (2)
   Hundrenths:        0DFF0H               33   (3)
   Thousands:         0DFF1H               34   (4)

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