You can submit your own busy or futile beavers.

### 4 bit addressing (16 byte memory)

*This is the category likely most interesting to breadboard-computer-havers.*

The program with the longest known **4-bit halting time** takes

- 3066 steps if only valid instructions are allowed.
- 3066 steps if invalid instructions are treated like no-ops.

The program with the longest known **4-bit loop cycle** has a cycle of

- 16 steps if only valid instructions are allowed.
- 16 steps if invalid instructions are treated like no-ops.

### 3 bit addressing (8 byte memory)

The program with the longest known **3-bit halting time** takes

- 131333 steps if only valid instructions are allowed.
- 131333 steps if invalid instructions are treated like no-ops.

The program with the longest known **3-bit loop cycle** has a cycle of

- 132352 steps if only valid instructions are allowed.
- 132352 steps if invalid instructions are treated like no-ops.

### 2 bit addressing (4 byte memory)

*
The paper and talk said that the busy beaver was 835, but this was due to two mis-implemented instructions.
It should not be possible to improve any further on the top "scores" in this category
(unless I made other mistakes). All 4 billion possible programs were tested, though not all were submitted.
*

The program with the longest known **2-bit halting time** takes

- 859 steps if only valid instructions are allowed.
- 859 steps if invalid instructions are treated like no-ops.

The program with the longest known **2-bit loop cycle** has a cycle of

- 1079 steps if only valid instructions are allowed.
- 1079 steps if invalid instructions are treated like no-ops.