[Simh] Why 36-bit computing?

[Bob Armstrong]

>By the time IBM introduced System/360, scientific calculations had shifted
>to floating point and mechanical calculators were no longer a competitor. 

  ... but the PDP-6 and the S/360 are roughly contemporary - both were
introduced around 1964.  I guess IBM was more forward thinking than DEC was
at the time :-)

  Of course DEC had a prior history with 18 bit computers, so I'm sure 36
seemed like a more natural choice.

Bob Armstrong