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         I N T E R P R E T E D    B A S I C    R E V I S I T E D     3. 
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     THISDAY.BAS is an example of a BASIC routine in conjunction with a DOS 
     batch  file, the idea being to implement some kind of a switch that is 
     operative the first time and only the first time that the computer was 
     booted up each day.  The gimmick, of course, is BASIC's TIMER function 
     which counts twenty four hours worth of seconds and then flips back to 
     zero.   Lines 10, 20, 50 and 70 are all that matter here; the rest are 
     bells and whistles.    
  
                5  REM Exit DOS batch file with "BASICA THISDAY.BAS"      

               10  CLS: Z=VAL:(MID$(DATE$,4,2)): X=INT(TIMER)  
               20  OPEN "TIMER.SEQ" FOR INPUT AS #1: INPUT #1, ZZ, XX  
               30  PRINT "previous time: " XX: PRINT "present time:  " X  
               40  PRINT "previous day:  " ZZ: PRINT "present day:   " Z  
               50  CLOSE #1:  ZZ=Z:  XX=X  
               60  OPEN "TIMER.SEQ" FOR OUTPUT AS #1: WRITE #1, Z, X  
               70  IF XX<X AND ZZ=Z THEN 80 ELSE 90  
               80  FOR J=1 TO 5: SOUND 523.25,2: SOUND 659.26,2: NEXT J  
               90  SYSTEM: REM  Exit BASIC and return to DOS  
