A character based FORTH where every word is one char long. Core implemented in less than 500 lines of x86-64 assembly.
:L 91+ 91+ * 91+ *; \ length
cA L8*a \ array of qwords
:t sdrdrs ; \ 2dup
\ do sieve for given number
:S 0 1W 1+ t* d L1->I DDDX T 8*A+ 1s! 1R;
\ print out all primes from 2 to L
:P 2 1W d 8*A+@ 1~=I d. dS T 1+d L-R;
Pb