J64, the 64 bit version of J, is now available.

• Address space is 64 bits (1.84e19 bytes) instead of 32 bits (4.29e9 bytes).
• Integers are 64 bits instead of 32 bits.
• As before, integer comparisons are exact (not tolerant).
• The default memory limit (Edit|Configure|Parameters... or 9!:20 and 9!:21) is 2^62 instead of 2^30 .
• 3&(3!:4) converts integers to sets of 8 characters; _3&(3!:4) computes the inverse.