non-binary computers?

From: Jay Jaeger <>
Date: Sun Sep 5 22:37:49 1999

Really, only the _normalization_. It was quantized at 4 bits. The number
itself was binary of course (hex being 4 bits).


At 05:24 PM 9/2/99 -0700, you wrote:
>The IBM 360 series was a "hexadecimal" machine. The result was that
>you got one or more fewer decimal digits of precision for floating
>point numbers as opposed to a binary machine. The CDC series of
>3xxx/6xxx was a favorite of scientifically oriented users due to
>this fact, and many computer centers were CDC instead of IBM at the
>time. (There was a difference in word length, too, but many users
>didn't realize that you could get better precision on a PDP-11
>than on a 360 in single precision.)
>The ultimate, of course, is the UNARY computer. If you look in the
>"Feynman Lectures on Computation", Richard Feynman, 1996, you'll see
>that he has you start designing a unary computer. Maybe not so easy
>when all you have to work with is "1"! (It has to have a variable
>word length, of course).
>Mark Green wrote:
>> > I recall reading an article a while back about the possibility of
>> > building computers based on a number system other than two (octal, IIRC).
>> > If memory serves me right, it was found possible to do, but not
>> > practical and less efficient than binary.
>> >
>> > I now have need for some basic information on the possibility of
>> > non-binary computers, but am unable to find anything. Can anybody point
>> > me in the direction of some info?
>> >
>> A number of early small computers were non-binary. One that comes
>> to mind is the IBM 1620 which was a decimal variable word lenght
>> machine. The 1620 was in production about 40 years ago and was
>> mainly marketed as a business machine. One of the interesting
>> features of this machine was that it did all its arthmetic by
>> table lookup. The tables were stored in memory, so you could change
>> how the operations worked! A number of 1620s were used by universities
>> into the late 1960s. Since they were variable word length, they
>> were very nice for doing precise computations.
>> Since early computers were based on analogue electronics it was
>> much easier to do non-binary than it is now. Many early memory
>> devices (except core) were really analogue devices with thresholds
>> used to distinguish 0 and 1. You just needed to add a few more
>> thresholds to get a larger range.
>> --
>> Dr. Mark Green
>> Professor (780) 492-4584
>> Director, Research Institute for Multimedia Systems (RIMS)
>> Department of Computing Science (780) 492-1071 (FAX)
>> University of Alberta, Edmonton, Alberta, T6G 2H1, Canada
Jay R. Jaeger The Computer Collection visit
Received on Sun Sep 05 1999 - 22:37:49 BST

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