Sign magnitude, one's complement, two's complement

[Sean Conner]

  For my own morbid curiosity, and because it came up on another mailing
list I'm on [1], what machines commercially avaialble were sign magnitude
and one's complement?  Every machine I've encountered was two's complement
(okay, IEEE 754 [2] is a sign magnitude format but I'm talking about integer
implementations here, not floating point).  I've only found reference to one
sign magnitude computer (the IBM 7090, release in 1959) and a few one's
complement machines (mostly the PDP series from DEC).  

  Where there others?  And honestly, are there any machines that use
anything other than two's complement today?  

  -spc

[1]	http://lua-users.org/lists/lua-l/2015-08/msg00386.html

[2]	AKA floating point.