To: Bill Lapson
From: Rickson Sun
Date: Oct. 16, 1980
Subject: Mouse Life Testing Memo
After an effective three years of running in circles on formica, the mouse has shown only minor degradation in performance.
The testing machine runs at the rate of 2473 ft/hour. With a usage estimate based on the following assumptions: 1.5 feet per edit, 1 edit per 10 seconds, 2 hours per day of editing activity, and 300 working days per year. This gives 324,000 ft/year, or 119 hours/year. With 385 hours total, the mouse has run for 3.24 years.
To check performance of the mouse a fixture was made up that constrained the mouse motions to up-down, left-right, diagonal lower left (LL)-upper right (UR), and lower right (LR)-upper lift (UL). Hysteresis was monitored qualitatively by watching the resulting cursor motion on Lisa.