15 August 2016

The IBM PC BASIC / Microsoft GW-BASIC version is identical to the Applesoft reference version apart from its taking advantage of the MODulus function available in this BASIC.

Even though this BASIC runs on a modern PC and would easily be fast enough to give a sensible result for n=10000, the integer type is a 16-bit signed quantity. It cannot express a result larger than 32768 and crashes after finding the 3512th prime.

 1 GOTO 10
 5 COUNT = COUNT + 1
 6 GOTO 50
 10 DIM PRIMES(99)
 20 PRIMES(0) = 2
 25 PRINT PRIMES(0)
 30 COUNT = 3
 40 FOR FOUND = 1 TO 99
 50 FOR INDEX = 0 TO (FOUND - 1)
 60 IF (COUNT MOD PRIMES(INDEX)) = 0 THEN GOTO 5
 70 NEXT INDEX
 80 PRINT COUNT
 90 PRIMES(FOUND) = COUNT
 100 COUNT = COUNT + 1
 110 NEXT FOUND
 120 END