In 1974, there was a short period when I wrote a specialized non-graphic program to look for large triangles and repeating patterns in the Triangles Pattern. It ran on an IBM system 360/40 with 128K. The results are not documented, although I know I did not find any repeating patterns.
In 1975, I wrote Martin Gardner, a columnist for Scientific American a letter describing how the patterns worked, as developed in the XPAND program, although some of the details regarding direction systems were revised and never implemented. I enclosed several sketches, printouts and a photographic slide of a recent drawing of the Line Pattern I created for this purpose. I had hoped Scientific American would do a cover story on it. [Correspondence dated August 23, 1975.]
In 1976 and 1977 there was more activity. I ported the IBM 1130 XPAND program to run on an IBM system 370/135 with 512K. This program grew Expansions in a full array, without the eight-way flipping routine developed to cope with the restricted memory available when I wrote the first version of XPAND. Through a friend, I had very limited and somewhat indirect access to an Information International VideoComp page composition system used for printing high resolution graphics. The patterns were grown on an IBM 370/145 or 148 with 2Meg, written to tape, and then converted to the VideoComp format by translating the pattern to the RCA Page-1 language and then compiling and executing it. The VideoComp was located in Allentown, Pa. The quality was excellent, but access was limited to a few precious evenings and the programs were not completely debugged. I was too involved with technical factors to find time to explore and make new discoveries. No new patterns were grown, but existing asymmetric patterns were seen in their "natural form" for the first time.
In 1977, I did some follow-up work in developing a "post-processing" program named "Expansions2". Expansions2 had options such as feeding a generated pattern into John Conway's game of "Life" rules or running pattern-matching and substitution routines with rotation, flipping and wild cards using three-by-three or five-by-five user specifiable cells. I ran the program perhaps a half-dozen times and output was restricted to a character-based printer, once again. Seeds for new ideas were sown, such as growing patterns via iterations of pattern-matching and substitution instead of vector lists, but I did not immediately follow-up these ideas. ["The Game of Life": See Martin Gardner's column "Mathematical Games" in Scientific American, October, November 1970, January, February, March, April, November 1971, and January 1972 for further information about John Horton Conway's game of "Life," a famous brand of cellular automata.]
Around this time began a seven-year period of Expansions inactivity.
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