Non-Spartan versions of Fx77 were in common use for many years to allow circuitry to be packed more tightly together, and especially to reduce the bounding boxes of guns in the original Hersrch-assisted completion of the p14-p999 glider gun collection. The "Fx77S" and "Fx77SW" forms below were specifically included in Hersrch's database for use in searches for Herschel loop guns with minimal bounding boxes.
This variant with an unnamed 23-cell still life[1] allows connections to following conduits with initial eater catalyst positioned as in Fx77 (click above to open LifeViewer) RLE:herePlaintext:here
This variant with an unnamed 39-cell still life[2] allows connections to following conduits with initial eater catalyst positioned as in F117 (click above to open LifeViewer) RLE:herePlaintext:here
Another common variant is the Spartan combination of an Fx77 with a following R64 conduit, as shown below. Just below the safe repeat time, at 210-tick separation between gliders, an extra output glider is produced.
In January 2016, Tanner Jacobi discovered a Spartan method of extracting an additional glider using a transparentpond.[3] In all of the these variants, as in the infobox, a ghost Herschel marks the output location.
This optimization is generally used only in glider-constructible circuitry, where recovery time is not an issue. It replaces two eater1s with a single block but increases the repeat time to 211 (click above to open LifeViewer) RLE:herePlaintext:here
Tanner Jacobi's Spartan Fx77 variant, producing an extra output glider often used in glider synchronization circuitry (click above to open LifeViewer) RLE:herePlaintext:here
Periodic glider extraction
On August 3, 1996, Buckingham noticed that a sparker can replace the blinker-suppressing eater, so as to produce an extra glider output in a different direction from FNG. This can be used to create glider guns from Herschel loops with period being a composite number; an example can be found in p57 Herschel loop 1.
