McGee Letter of Reference

"In 1975, I finished up in Lynbrook High School in the mornings, and attended DeAnza Junior college in the evenings. In the afternoons and following school, I worked at NASA-Ames Flight Systems Navigation (FSN) branch for Leonard McGee, who loaned me out at times to various projects to 'fight fires'.

Leonard was working on an elaborate program called VSTOLAND, which was involved with the XV-15 Tilt Rotor program. A simulation of the navigational software that would combine inertial guidance and VOR/DME navigational aids, its Kalman Filtering would be subtracting out modeled error for a better fix. Numerical glitches in floating point often created interesting surprises in the statistics used to do this, so going from a IBM 360 (base 16 exponent - see computer below) to a CDC 7600 (binary exponent - see computer above) had interesting effects in the numbers."

One of the interesting aspects of NASA at the time was the variety of programming environments, hardware, nomenclature, vendors, etc. Nothing was the same. Assembly languages, Fortran, Basic, each machine a different variation, with different roundoff errors and other quirks. Often the errors propagated into the results.

The ArpaNet was present to go across the country, but on campus it was asynchronous serial communications, without file transport, and often 1200/2400 baud.