HL = pointer to 6 byte date and time. First 3 bytes are time in
internal format, second 3 bytes are date in internal format.
Registers changed after return:
Date strings are fully country localized since OZ 4.5. It displays today, yesterday or tomorrow using the localized string.
Will fail if address pointer is in segment 2.
GN_Gmt, get (read) machine time in internal format
GN_Gtm, convert an ASCII string to a time in internal format
GN_Msc, miscellaneous time operations
GN_Pmt, put (set) machine time
GN_Ptm, write internal time as ASCII string
OS_Dly, delay a given period