zlacker

One very small correction: QUIKTRAN wasn't a “mathematical utility”, but an early timesharing system, I think running on a 7044 (coincidentally, my first mainframe). It offered an interactive Fortran system, with editing and debugging facilities. IBM's later CALL/360 system was a successor to this, adding PL/I and Basic.

Interesting UX fact: IBM researchers looked at user satisfaction on this system. They found that it wasn't poor response time that bothered people, but variability of response times. If users couldn't predict how long an operation would take, that bothered them. So they inserted delays so that average response times were maybe longer, but variance was lower. And users were happier.