three states, no bits

A balanced ternary computer, specified and running in your browser

Every digit is -1, 0, or +1. Six of them make one word. This site documents the architecture and gives you a working machine to write for.

Open the playground Read the specification

word: 6 trits
states per word: 729
range: -364 .. 364
memory: 729 words
registers: R0 .. R7, PC, SP, FLAGS
instruction: 3 words, fixed width

word dial

set each switch to - 0 +

243

reads000+0-9 -1 =8

Numbers, without a sign bit

Negative values fall out of the notation itself: flip every trit and you have the negation. Leading zero trits are dimmed so the significant part of a word reads first.

decimal	word	weights
-364	------	-243 - 81 - 27 - 9 - 3 - 1
-13	000---	-9 - 3 - 1
-1	00000-	-1
0	000000	0
1	00000+	1
8	000+0-	9 - 1
121	0+++++	81 + 27 + 9 + 3 + 1
364	++++++	243 + 81 + 27 + 9 + 3 + 1

A program, end to end

add.tas

START:
    MOV   R1, +0-      ; R1 = 8
    MOV   R2, 5
    ADD   R1, R2       ; R1 = 13
    STORE [100], R1
    HALT

Load this and six other example programs — including Fibonacci with visible overflow — in the playground, where the assembler reports errors by line and the machine can be stepped one instruction at a time.