A project log for Tern - Ternary Logic Circuits

A series of ternary logic gates and higher level components implemented in the real world.

The simplest gates are those which only take one input have only one output. Monadic gates are important building blocks to more complex/useful gates, but they can be useful by themselves in some circumstances. In binary there are only 4 of these (2^2 = 4) but in ternary systems there are 27 (3^3 = 27). Much of what I am trying to demonstrate is described in Dr. Douglas W. Jones' description of ternary logic and I use his naming conventions.

Buffer/Driver

 In Out 0 0 1 1

Inverter

 In Out 0 1 1 0

Constant 0 (not really useful, but here for completeness)

 In Out 0 0 1 0

Constant 1 (not really useful, but here for completeness)

 In Out 0 1 1 1

 0 1 2 3 4 5 6 7 8 9 A B C D E F G H K M N P R T V X Z - - 0 + - 0 + - 0 + - 0 + - 0 + - 0 + - 0 + - 0 + - 0 + 0 - - - 0 0 0 + + + - - - 0 0 0 + + + - - - 0 0 0 + + + + - - - - - - - - - 0 0 0 0 0 0 0 0 0 + + + + + + + + +

(The labels in the top row are names for a series of three trits. Just like hexadecimal is just a naming scheme for series of 4 bits. This system is called heptavintimal - base 27)

The goal is to test the two devices I am using (a Fairchild Semiconductor LM319 dual comparator and a Motorola LM393 dual comparator) and see which monadic operations they can produce. Three of the operations (0, D, and Z) are trivial because they are always -, 0, or +. That is equivalent to just attaching the signal to the appropriate -5V, GND, or +5V rail. That leaves only 24 monadic operations to work out.

The comparators have a - input and a + input. If the + input is greater than the - input then the output line allows current to flow through it to ground. The LM393 allowed me to use both the +5V and the GND lines on the output pin but the LM319 only allowed me to use +5V. That made the LM393 more versatile, but the LM319 handled low signals differently. Low signals on the LM319 returned GND while the LM393 returned -5V for it's low signal. The result is that both devices would produce a subset of the monadic operations, but each was a different subset. Together they took care of 12 possible combinations. Add that to the 3 trivial operations and there are 15 out of 27 monadic operations accounted for using just the power rails, or only a single comparator.

The LM393 can produce the following monadic operations: 1,2,4,8,9,C,K, and V. Diagram

The LM319 can produce the following monadic operations: E,H,R, and X. Diagram

If you look carefully you'll notice the pattern that each monadic operation we can produce is a pattern of 2 outputs that are the same and one that is different. Also, the one that is different is alway the top or bottom one, never the middle. This is a consequence of how a comparator always chooses the greater of two inputs to make it's decision as to whether or not to output. Hopefully, by chaining together the monadic gates now possible I can make the remaining ones.