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Purpose: Read system clock Call address: $FFDE (hex) 65502 (decimal) Communication registers: A, X, Y Preparatory routines: None Error returns: None Stack requirements: 2 Registers affected: A, X, Y |
Description:
This routine is used to read the system clock. The clock's resolution is a 60th of a second. Three bytes are returned by the routine. The accumulator contains the most significant byte, the X index register contains the next most significant byte, and the Y index register contains the least significant byte.
EXAMPLE:
JSR RDTIM
STY TIME
STX TIME+1
STA TIME+2
...
TIME *=*+3