Several early computer designs regarded a 'word' as representing not an integer, with the bits having values 2^0, 2^1, 2^2, ..., but as representing a fixed-point fraction 2^-1, 2^-2, 2^-3, ...
(For the sake of simplicity in this question I'm ignoring the existence of the sign bit and talk only in terms of positive numbers)
Some examples of this convention are EDVAC, EDSAC, and the IAS machine.
Why was this? To me, having dealt with since the 1970s with machines that have "integers" at base, this seems a strange way to look at it.
Does it affect the machine operation in any way? Addition and subtraction are the same regardless of what you think the bits mean, but I suppose that for multiplication of two N-bit words giving an N-bit result, the choice of which N bits to keep depends on your interpretation. (Integer: you want the "right hand word"; fixed-point fraction, you want the "left hand word").