Harland Harrison

A printed circuit board (PCB), sheet metal design, and manufacturing package for a unique PCB factory run entirely by macOS computers

As the only software engineer, I wrote CAD/CAM software for designing printed circuit boards (PCBs) and control software for a unique PCB factory run entirely by MacOS computers. I used the Assembly language to drive stepper motors directly and to write custom copy protection and a tracking system. I interfaced motor controllers with USB, RS422. and ethernet and maintained this factory system for decades. The project included C/C++, UNIX, XCode, Apple libraries, and SDKs.

Broca's area is usually located in the cerebral hemisphere associated with the dominant hand. While about 10% of humans are left-handed, other animals with limb preferences exhibit a near-equal left-to-right ratio. At birth, the two brain hemispheres appear identical, and the mechanisms underlying hemispheric dominance remain unclear.

This simulation tests the hypothesis that hemispheric dominance is mainly developmental, with the widespread right-handedness resulting from the amplification of an initial, subtle bias. Although the corpus callosum connects the hemispheres, its long fibers transmit information slowly, suggesting that learned skills may concentrate in one hemisphere.

The simulation analyzes texts to extract vocabulary, randomly assigning new words to one hemisphere or another. When a sequence of three known words is encountered, with the middle word in the opposite hemisphere of the outer two, it is randomly reassigned. The results show that most words tend to concentrate in one hemisphere after processing approximately one million words—the number of words an infant typically hears in their first year. When a slight bias is introduced toward one hemisphere, most runs, though not all, favor the side with the bias.

As the only iOS developer, I wrote the Chiro iOS app to emulate a physical device called the ThermoGraph used by chiropractors. Chiro reads serial data transmitted by RF from an Arduino device, processes the data, and displays a simulated live paper strip chart. Chiro also edits, saves, and exports ID information. As a result, a bulky, custom, physical hardware device could be entirely replaced by the phone the doctor already had.