Timer and Counter Instructions
Chapter 5
524
The execution time, T, in microseconds for the complete mode is:
T = 99 + 9.8 (Words operated upon per scan) + 14.4 (Number of 256
word blocks operated upon per scan)
Example: What is the execution time to perform a File-to-File AND
operation on two files 670 words long? The rate per scan is 256 and the
mode is the distributed complete mode.
T = 125 + 9.8(256) + 14.4(2) = 125 + 2509 + 28.8 = 2663
T = 2663 microseconds = 2.66 milliseconds.
The incremental mode requires approximately 100 microseconds per scan.
When the instructions are false, they require 6 microseconds.
The first scan the rung is false after the done bit is set requires 17.6
microseconds to reset flags and counters.
Table 5.G
Average Execution Times In Microseconds For FILETOFILE AND, OR,
XOR Instructions When Instruction Is TRUE
Time (Microseconds)
Rate (Words per Scan) Dist. Complete Mode
Complete Mode
5
10
15
25
50
100
256
512
174
223
272
370
615
1105
2648
5171
148
197
246
344
589
1079
2622
5145
Formulas for more exact approximations can be found in Section 5.6.4.
Execution time for Incremental mode is 100 microseconds per scan. When FALSE, execution time is 6 microseconds. Time
required to reset flags and counters is 17.6 microseconds.
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