# Is there a difference between pure binary and binary?

In some books and on the internet I occasionally find "pure binary" and "binary" on its own, is there a difference between these two terms? If so, can someone describe briefly what they are?

• What is the context? – Aryabhata Apr 21 '13 at 14:22
• @Aryabhata I found it to be in a section about Gray Code, where only the term "pure binary" is used, while "binary" is used in the rest of the book. – Saras Apr 21 '13 at 17:18

I'm guessing here for lack of context, but I think the following distinction is reasonable.

A binary encoding is anything that maps stuff to bit strings. There are many, including two's complement, IEEE float, ASCII, and so on.

Pure binary probably refers to bland natural numbers written in base two, i.e. if $n_{(2)} = a_k\dots a_0$ then

$\qquad\displaystyle n = \sum_{i=0}^{k} 2^ia_i$.

• So pure binary refers to binary pattern that has not been modified in any way or is not a fixed-point binary number and not a signed integer, etc. Just the natural denary number converted to binary? – Saras Apr 21 '13 at 17:26
• That's what I'm saying, but I can't promise that everybody will use the terms like that in every context. – Raphael Apr 21 '13 at 22:58

The only contexts I know where pure binary is used when referencing the C standard which has a definition for the concept

A positional representation for integers that uses the binary digits 0 and 1, in which the values represented by successive bits are additive, begin with 1, and are multiplied by successive integral powers of 2, except perhaps the bit with the highest position.

The rationale for the C standard mentions the desire to avoid things like Gray code.