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ETA is an esoteric programming language designed by Mike Taylor in 1999. The name comes from its instruction set, based on the eight most common letters in the English language: E, T, A, O, I, N, S, H. "Eta" is also the seventh letter in the Greek alphabet, and ETA uses base-7 numbering. The language is stack-based and all characters that are not instructions are treated as comments. Eta has 7 instructions:
|Command||What it does|
|E||Pop two numbers of the stack, first b, then a.Then push floor(b/a) first and b%a second.|
|T||Pop 2 numbers off the stack, first |
|A||Push the current instruction number.|
|O||Print and pop top of stack as an ASCII character|
|I||Push the input as an ASCII character|
|N||Push a base-7 number. The digits are:|
H=0 T=1 A=2 O=3 I=4 N=5 S=6. E terminates the number.
|S||Pop 2 numbers off the stack: first b, then a. Push b-a on the stack.|
|H||Pops a number n from the stack.|
If n>0 then remove the
If n<=0 then push the
If n=0, this is effectively a DUP.