Data Processing Techniques - All about the IBM 1130 Computing ...

Section Subsections Page90 30 20 04printer. For example, an analysis that indicates a1403 speed of 450 1pm must be modified if the printerconsidered is a 1403-6, which cannot exceed 340 1pm.The 750-millisecond time for the 1132 is based onstandard FORTRAN, which is not overlapped.The 176 (or 100) millisecond time for the 1403consists mainly of the conversion from EBCDIC to1403 code - the 1403 itself is buffered, and the timerequired to fill the buffer is quite small. The 176milliseconds drops to 100 on a 2.2 microsecondCPU because of the faster CPU. See the next subsection.ComputingThe 1131 Central Processing Unit is available withone of two basic cycle times: 3.6 microseconds(Models 1 and 2) or 2.2 microseconds (Model 3). Inmore basic terms, the Model 3 will compute in .61the time of the Model 1 or 2.However, in this area it is not quite as easy tocalculate the improvement to be expected from thefaster CPU. The problem is that you often don'tknow how much time you were computing before(with a 3.6-microsecond CPU), in which case youcannot possibly tell what effect the 2.2-microsecondCPU will have.Let us review the previous example: 1442-6 and1132; ten minutes run time, read 600 cards, print600 lines, skip 100 lines. The times in milliseconds,were:Card read 120,000Print and skip 451,600"Everything else" 28,400Total 600,000 (10 minutes)The only way you determined the 28,400 millisecondsof "everything else" was by subtracting one knownvalue (I/O times) from another known value (totalrun time).If you know that all 28,400 milliseconds werespent in computing, you can calculate that the 2.2-microsecond CPU will do the same amount of workin 61% of that time, or 17,300 milliseconds, areduction of 1,100 milliseconds or 1.8 minutes.If those 28,400 milliseconds had included any diskoperations, you could not have made the above estimate,since you would have had no way to determinethe split between disk activity and computing. Asidefrom a good estimate, which would be quite anachievement, the only way to evaluate the effect ofa new CPU in this case would be to take your programto such an 1130, run it, and time it.