INTRODUCTION The Keithley Model 193A System DMM, with the TRMS AC Volt and Current options installed, is a six function autoranging digital multimeter. At 6 1/2 digit resolution, the LED display can display ±2,200,000 counts. The range of this analog-to-digital (A/D) converter is greater than the normal ±1,999,999 count A/D converter used in many 6 1/2 digit DMMs. The built-in IEEE-488 interface makes the instrument fully programmable over the IEEE-488 bus. With the TRMS ACV option and the Current option installed, the Model 193A can make the following basic measurements: 1. DC voltage measurements from 1OOnV to 1000V. 2. Resistance measurements from 100µΩ to 200MΩ. 3. RTD temperature measurements from -100°C to 630°C. 4. TRMS AC voltage measurements from 1µV to 700V. 5. DC current measurements from 1nA to 2A. 6. TRMS AC current measurements from 1nA to 2A.