4 August 2018

Apple FORTRAN for the Apple ][ is supposedly based on FORTRAN-77 but I found it to be unhappy unless the source more closely resembles FORTRAN-66. * is allowed as an I/O unit, but the output format for the console must be explicitly specified. Also, STOP requires a string argument, which is printed on the console.

      INTEGER FOUND, COUNT, I, PRIMES(100)

      FOUND = 0
      COUNT = 2   
       
10    FOUND = FOUND + 1
      WRITE (*,'(I6)') COUNT
      PRIMES(FOUND) = COUNT
      COUNT = COUNT + 1

      I = 1
      IF (FOUND .LE. 100) THEN
20      IF (MOD(COUNT,PRIMES(I)) .EQ. 0) THEN
          COUNT = COUNT + 1
          I = 1
        ELSEIF (I .EQ. FOUND) THEN
          GOTO 10
        ENDIF
        I = I + 1
        GOTO 20  
      ELSE
        GOTO 30
      ENDIF
         
30    STOP 'Done.'
      END