ETA

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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:

Instruuctions
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 addr, then cond. If cond!=0 then jump to the addrth instruction. The first instruction is instruction 1. Jumping to instruction 0 terminates the program.
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.
Example: NTONE=(1x7^2+3x7^1+5x7^0)
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 nth value and push it on top of stack.
If n<=0 then push the nth item onto top of stack and keep the original one intact unlike the top case.
If n=0, this is effectively a DUP.

See also

External resources