via HACKADAY: Retro Gadgets: The 1983 Pocket Oscilloscope

In the 1980s, an oscilloscope was typically a bulky affair with a large CRT, and a heavy power supply. So it probably grabbed a lot of attention in 1983 when Calvert Instruments Incorporated ran an ad in magazines like Radio Electronics. The ad touted a 5 MHz scope that was pocket-sized and weighed 4 ounces. The ad proudly proclaimed: CRT oscilloscopes just became obsolete!

Indeed they would, but if you are wondering who Calvert Instruments was, so are we. We have never heard of them before or since, and we don’t know for certain if any of these devices were ever actually produced. What did it use instead of a CRT? The CI Model 210 Pocket-O-Scope was not only solid state but used an LED screen 1.5 inches square. That’s small, but it packed in 210 LEDs for “high resolution.” We assume that was also the genesis of the model number. Judging from the product picture, there were 14 LEDs in the X direction and 15 in the Y direction. High resolution, for sure!