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

Section Subsections Page90 30 20 02The 2501, because of its clutch arrangement,requires a special analysis. The 2501-Al, the 600-card-per-minute reader, will read at fixed speeds of600 cpm (100 millisec)300 cpm (200 millisec)200 cpm (300 millisec)150 cpm (400 millisec)120 cpm (500 millisec)100 cpm (600 millisec)etc.and the 2501-A2, the 1000-card-per-minute reader,will read at fixed speeds of1000 cpm (60 millisec)500 cpm (120 millisec)333 cpm (180 millisec)250 cpm (240 millisec)200 cpm (300 millisec)166 cpm (360 millisec)etc.To calculate the expected improvement in timingdue to a 2501-Al, we must, as before, substitute100 milliseconds for the 200 milliseconds (1442-6),to get 2100 x 100 or 210,000 milliseconds readtime, add the 180,000 milliseconds other time,obtaining 390,000 milliseconds or 15 minutes.Dividing this into the number of cards read (3000),we find that this yields a rate of 323 cards perminute.However, the clutch arrangement of the 2501-Alwill not allow it to run at 323 cards per minute, sothe next lower speed (300 cpm) must be assumed.2100 cards at 300 cpm yields a total time of sevenminutes.A similar analysis for the 2501-A2 gives atheoretical speed of 412 cpm, but, choosing the nextlower speed, 333 cpm, the total run time is calculatedas 6.6 minutes.-8Card PunchingThree different card punches are available for use onthe 1130 system; all three operate in the same mode,punching one column at a time.Card Punch Milliseconds per Card ColumnPunched or Spaced1442 Model 6 12.5 plus 12.5 per column1442 Model 7 6.5 plus 6.5 per column1442 Model 5 6.5 plus 6.5 per columnModels 6 and 7 both read and punch; Model 5 onlypunches.The overall speed is determined by the lastcolumn punched, rather than the number of columnspunched. If you skip the first 20 columns and punchinto the 21st, you have punched or spaced 21 columnsand the time for that number will apply. Figure90.10 gives the punching time for the three models,as they vary with the last column punched.To continue the previous example, suppose thatof the 2100 cards read, the program punched intoF31000900800700600500400300200100Last Column PunchedFigure 90.10.