84h DP$CPRN redefine the clock UDGs
Input A register - 0 to define UDG 5 only.
Output - none -

Re-defines the UDGs used for the clock as the current system time.

If the A register is 0, just UDG 5 is defined (the flashing colon). Defines UDG 5 as ":" if the top bit of DPB_CRED is set, otherwise defines UDG 5 as "_".

The screen status (cursor position etc) is always preserved.

This call is not available on CM/XP machines.

Errors - none -