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Chapter 6. Service Request Function
6.30 SVC_REQ 50: Read Elapsed Time Clock
Use SVC_REQ 50 to read the system's elapsed time clock. The elapsed time clock measures the time
in seconds since the CPU was powered on. The parameter block has a length of four words used for
output only.
Output
Address
Seconds from power on (low order)
Address+1
Seconds from power on (high order)
Address+2
nanosecond ticks (low order)
Address+3
nanosecond ticks (high order)
The first two words are the elapsed time in seconds. The second two words are the number of
nanoseconds elapsed in the current second.
The resolution of the CPU's elapsed time clock is 100 µs. The overall accuracy of the elapsed time
clock is ±0.01%. The accuracy of an individual sample of the elapsed time clock is approximately
105 µs.
328
PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
The SVC_REQ instruction is not protected against
operating system and user interrupts. The timing and
length of these interrupts are unpredictable. The clock
sample returned by SVC_REQ 50 can sometimes be
much more than 105 µs old by the time execution is
returned to the LD logic.
Warning
GFK-2950C
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