Dialects
The original Woods–Lyon INTERCAL was very limited in its input/output capabilities: the only acceptable input were numbers with the digits spelled out, and the only output was an extended version of Roman numerals. A while later, there was an 'Atari implementation', about which notes are provided in the INTERCAL reference manual; it 'differs from the original Princeton version primarily in the use of ASCII rather than EBCDIC'.
The C-INTERCAL reimplementation, being available on the Internet, has made the language more popular with devotees of esoteric programming languages. The C-INTERCAL dialect has a few differences from original INTERCAL and introduced a few new features, such as a COME FROM statement and a means of doing text I/O based on the Turing Text Model.
The authors of C-INTERCAL also created the TriINTERCAL variant, based on the Ternary numeral system and generalizing INTERCAL's set of operators.
A more recent variant is Threaded Intercal, which extends the functionality of COME FROM to support multithreading.
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