CMOS clock, 3 kinds of event available, all in even multiples or fractions
of calendar seconds.  

The cycluphone and harmony engine might go in here.
They might run off of subsecond walltime.


It seems epoch time ala unix predates calendar clock hardware. I'm
thinking keep system ticks and calendar time separately and keep system
variables for timezone/politicizations and tick period. The tick period
variable should be in Hz. We also can keep just uptime and not timestamps,
and let timestamps be a syscall. Decisions, decisions....

# Ralf sez.....
#0070  -W  CMOS RAM index register port (ISA, EISA)
#                 bit 7  = 1  NMI disabled from reaching CPU
#                        = 0  NMI enabled
#                 bit 6-0     CMOS RAM index
#                        (64 bytes in early systems, now usually 128 bytes)
#        Note:   any write to PORT 0070h should be followed by an action to
#                  PORT 0071h or the RTC wil be left in an unknown state.
#0071  RW  CMOS RAM data port (ISA, EISA) (see #P0409)

PC calendar clocks aren't very accurate, historically. There are complex
schemes to check them against other clocks, but none is very pleasing.
None seem suitable for inclusion in a kernel.
