20 August 2016

On the ZX-80, one must use LET for assignment, pause when the screen is "full", and do without either INTeger or MODulus! So this version must rely on the use of integer-only division results for calculating a remainder explicitly and use PRINT; so that all the results fit on the screen at once.

Trying to use FOR/NEXT as the Applesoft version did results in stack exhaustion after a handful of results. Since there is no other kind of loop available in ZX-80 BASIC, we must make do with only GO TO—one final peculiarity (though irrelevant) is the tokenization of GO TO, where other BASICs use GOTO.

10 DIM P(99)
20 LET C=2
30 LET F=0
40 PRINT C;
50 LET P(F)=C
60 IF F=99 THEN GO TO 160
70 LET F=F+1
80 LET C=C+1
90 LET I=0
100 LET R=C-(C/P(I))*P(I)
110 IF R=0 THEN LET I=F+1
120 IF I>F THEN GO TO 80
130 LET I=I+1
140 IF I=F THEN GO TO 40
150 GO TO 100
160 STOP