Sieve of Eratosthenes benchmarks for the Z8 FORTH microcontroller

5. THE GILBREATHS’ FORTH PROGRAM FOR THE SIEVE ALGORITHM
The FORTH version of the Gilbreaths’ benchmark, as presented in their BYTE articles, is
shown below:
1.
2.
3,
4.
5.
6.
7.
8.
9.
10.
14”
12.
13.
ai90 CONSTAMT SIZE
0 VARIABLE FLAGS SlZE ALLOT
: OO-PRIHE
FLAGS SIZE 1 FILL
0 SIZE 0
DO FLAGS I + C8
IF I DUP + 3 + DUP I +
THEN
BEGIN DUP SIZE <
UHILE 0 OVER FLAGS + C! OVER + REPEAT
DROP DROP I+
LOOP
. .I‘ PRIMES“ ;
The Gilbreaths admit they are not skilled FORTH programmers; unfortunately, their
FORTH program reflects their lack of skill. There are two errors in the programs that
must be corrected to obtain correct res~lts.~ First, the condition for testing the
completion of the BEGIN ... WHILE ... REPEAT (lines 8 and 9) loop is erroneously written as
BEGIN DUP SIZE