27 years later, I stumbled upon this CA in the Rule Table Repository, and the patterns I found in the corresponding file (which were converted from the paper) really pleased me. Unlike other UCC-oriented CAs, the signals move through empty space (albeit at c/2). The basic building blocks, an eater and a fanout device, take up only one and two cells respectively. Combine this with the varied collection of two-signal interactions, and CA heaven was right in front of me. Only, where would I start?

Attached is the RTR's Serizawa package (minus the scan of the 1986 paper, which takes up way too much space), and two patterns I've created. The first is a triggerable clock, essential for a UCC. The second is a double ANDNOT gate like that used in the LCD ROM of the Wireworld computer.

Code: Select all

```
#N Triggerable clock in Serizawa
#O Jeremy Tan (Freywa / Parcly Taxel)
#C A p128 clock that can be activated by an external glider.
#C Essential for constructing a universal computer/constructor.
x = 36, y = 23, rule = Serizawa
16.A.A$17.B3$5.A6.A9.A$16.A.A11.A3$4.A24.A.A$.A33.A$4.A11.A6$31.A$A$
4.A.A24.A3$5.A$30.A!
```

Code: Select all

```
#N ANDNOT gate
#O Jeremy Tan (Freywa / Parcly Taxel)
#C Action H in Serizawa (1986) is equivalent to computing
#C A ANDNOT B or B ANDNOT A, depending on which output is considered.
#C This pattern demonstrates both possibilities.
x = 99, y = 49, rule = Serizawa
56.A.A6.A12.A.A2$56.A3.A3.A.A10.A3.A$70.A.A.A$56.A.A4.A3.A9.A.A.A$74.
A$56.A3.A16.A3.A2$56.A.A18.A3.A2$14.A$39.A18.A2$58.A$13.A24.A.A$.A.A
6.A33.A13.A$13.A$A3.A53.A2$A.A.A69.A.A5.A11.A.A$55.A5.A$A3.A68.A3.A3.
A.A10.A3.A$21.A15.A2.A46.A.A.A$A3.A4.A12.B15.B25.A.A.A.A2.A.A.A2.A3.A
9.A.A$13.A.A5.A15.A2.A50.A$73.A3.A16.A3.A$61.A$14.A58.A3.A16.A.A$39.A
2$33.A4$32.A18.A5.A.A$29.A20.B12.A4.A.A$32.A18.A$68.A3.A2$68.A.A2$68.
A3.A$56.A2.A$28.A28.B4.A5.A.A$32.A.A21.A2.A3$33.A$58.A!
```