Texas Instruments' "electronic slide rule"—their response to the HP-35. The SR stood for "Slide Rule," explicitly targeting the instrument it would replace.
Price: $149.95 (about $1,000 today)—less than half the HP-35's $395. It had square root, reciprocal, x², and scientific notation, displayed on a bright red LED display.
TI could undercut HP because they manufactured their own chips. The TMS0120 was an early single-chip calculator IC. Within a year, TI drove calculator prices below $100.
Number keys, basic ops, sqrt, 1/x, x² • Try "vs Slide Rule" mode for a comparison